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Sample records for extracellular bacterial pathogen

  1. Intracellular phase for an extracellular bacterial pathogen: MgtC shows the way

    PubMed Central

    Bernut, Audrey; Belon, Claudine; Soscia, Chantal; Bleves, Sophie; Blanc-Potard, Anne-Béatrice

    2015-01-01

    Pseudomonas aeruginosa is an extracellular pathogen known to impair host phagocytic functions. However, our recent results identify MgtC as a novel actor in P. aeruginosa virulence, which plays a role in an intramacrophage phase of this pathogen. In agreement with its intracellular function, P. aeruginosa mgtC gene expression is strongly induced when the bacteria reside within macrophages. MgtC was previously known as a horizontally-acquired virulence factor important for multiplication inside macrophages in several intracellular bacterial pathogens. MgtC thus provides a singular example of a virulence determinant that subverts macrophages both in intracellular and extracellular pathogens. Moreover, we demonstrate that P. aeruginosa MgtC is required for optimal growth in Mg2+ deprived medium, a property shared by MgtC factors from intracellular pathogens and, under Mg2+ limitation, P. aeruginosa MgtC prevents biofilm formation. We propose that MgtC has a similar function in intracellular and extracellular pathogens, which contributes to macrophage resistance and fine-tune adaptation to the host in relation to the different bacterial lifestyles. MgtC thus appears as an attractive target for antivirulence strategies and our work provides a natural peptide as MgtC antagonist, which paves the way for the development of MgtC inhibitors.

  2. Differential regulation of Sciaenops ocellatus viperin expression by intracellular and extracellular bacterial pathogens.

    PubMed

    Dang, Wei; Zhang, Min; Hu, Yong-hua; Sun, Li

    2010-08-01

    Viperin is an antiviral protein that has been found to exist in diverse vertebrate organisms and is involved in innate immunity against the infection of a wide range of viruses. However, it is largely unclear as to the potential role played by viperin in bacterial infection. In this study, we identified the red drum Sciaenops ocellatus viperin gene (SoVip) and analyzed its expression in relation to bacterial challenge. The complete gene of SoVip is 2570 bp in length and contains six exons and five introns. The open reading frame of SoVip is 1065 bp, which is flanked by a 5'-untranslated region (UTR) of 34 bp and a 3'-UTR of 350 bp. The deduced amino acid sequence of SoVip shares extensive identities with the viperins of several fish species and possesses the conserved domain of the radical S-adenosylmethionine superfamily proteins. Expressional analysis showed that constitutive expression of SoVip was relatively high in blood, muscle, brain, spleen, and liver, and low in kidney, gill, and heart. Experimental challenges with poly(I:C) and bacterial pathogens indicated that SoVip expression in liver was significantly upregulated by poly(I:C) and the fish pathogen Edwardsiella tarda but down-regulated by the fish pathogens Listonella anguillarum and Streptococcus iniae. Similar differential induction patterns were also observed at cellular level with primary hepatocytes challenged with E. tarda, L. anguillarum, and S. iniae. Infection study showed that all three bacterial pathogens could attach to cultured primary hepatocytes but only E. tarda was able to invade into and survive in hepatocytes. Together these results indicate that SoVip is involved in host immune response during bacterial infection and is differentially regulated at transcription level by different bacterial pathogens.

  3. An Extracellular Bacterial Pathogen Modulates Host Metabolism to Regulate its Own Sensing and Proliferation

    PubMed Central

    Baruch, Moshe; Belotserkovsky, Ilia; Hertzog, Baruch B.; Ravins, Miriam; Dov, Eran; McIver, Kevin S.; Le Breton, Yoann S.; Zhou, Yiting; Youting, Catherine Cheng; Hanski, Emanuel

    2014-01-01

    SUMMARY Successful infection depends on the ability of the pathogen to gain nutrients from the host. The extracellular pathogenic bacterium group A Streptococcus (GAS) causes a vast array of human diseases. By using the quorum sensing sil system as a reporter, we found that during adherence to host cells GAS delivers streptolysin toxins creating endoplasmic reticulum stress. This in turn, increases asparagine (ASN) synthetase expression and the production of ASN. The released ASN is sensed by the bacteria altering the expression of ~17% of GAS genes of which about 1/3 are dependent on the two-component system TrxSR. The expression of the streptolysin toxins is strongly upregulated whereas genes linked to proliferation are downregulated in ASN absence. Asparaginase a widely used chemotherapeutic agent, arrests GAS growth in human blood and blocks GAS proliferation in a mouse model of human bacteremia. These results delineate a pathogenic pathway and propose a new therapeutic strategy against GAS infections. PMID:24439371

  4. Effector proteins of the bacterial pathogen Pseudomonas syringae alter the extracellular proteome of the host plant, Arabidopsis thaliana.

    PubMed

    Kaffarnik, Florian A R; Jones, Alexandra M E; Rathjen, John P; Peck, Scott C

    2009-01-01

    In plants, potential pathogenic bacteria do not enter the host cell. Therefore, a large portion of the molecular interaction between microbial pathogen and host occurs in the extracellular space. To investigate potential mechanisms of disease resistance and susceptibility, we analyzed changes in the extracellular proteome, or secretome, using the Arabidopsis-Pseudomonas syringae pathosystem. This system provides the possibility to directly compare interactions resulting in basal resistance, susceptibility, and gene-specific resistance by using different genotypes of Pseudomonas on the same host. After infecting suspension-cultured cells of Arabidopsis with the Pseudomonas strain of interest, we isolated protein from the cell culture medium representing the secretome. After one-dimensional gel separation and in-gel digestion of proteins, we used iTRAQ (isobaric tags for relative and absolute quantitation) labeling in conjunction with LC-MS/MS to perform relative quantitative comparisons of the secretomes from each of these interactions. We obtained quantitative information from 45 Arabidopsis proteins that were present in all three biological experiments. We observed complex patterns of accumulation, ranging from proteins that decreased in abundance in the presence of all three bacterial strains to proteins that specifically increased or decreased during only one of the interactions. A particularly intriguing result was that the virulent bacteria (e.g. a susceptible interaction) caused the extracellular accumulation of a specific subset of host proteins lacking traditional signal peptides. These results indicate that the pathogen may manipulate host secretion to promote the successful invasion of plants.

  5. Bacterial extracellular lignin peroxidase

    DOEpatents

    Crawford, Donald L.; Ramachandra, Muralidhara

    1993-01-01

    A newly discovered lignin peroxidase enzyme is provided. The enzyme is obtained from a bacterial source and is capable of degrading the lignin portion of lignocellulose in the presence of hydrogen peroxide. The enzyme is extracellular, oxidative, inducible by lignin, larch wood xylan, or related substrates and capable of attacking certain lignin substructure chemical bonds that are not degradable by fungal lignin peroxidases.

  6. BACTERIAL WATERBORNE PATHOGENS

    EPA Science Inventory

    Bacterial pathogens are examples of classical etiological agents of waterborne disease. While these agents no longer serve as major threats to U.S. water supplies, they are still important pathogens in areas with substandard sanitation and poor water treatment facilities. In th...

  7. BACTERIAL WATERBORNE PATHOGENS

    EPA Science Inventory

    Bacterial pathogens are examples of classical etiological agents of waterborne disease. While these agents no longer serve as major threats to U.S. water supplies, they are still important pathogens in areas with substandard sanitation and poor water treatment facilities. In th...

  8. Flagella and bacterial pathogenicity.

    PubMed

    Duan, Qiangde; Zhou, Mingxu; Zhu, Liqian; Zhu, Guoqiang

    2013-01-01

    As locomotive organelles, flagella allow bacteria to move toward favorable environments. A flagellum consists of three parts: the basal structure (rotary motor), the hook (universal joint), and the filament (helical propeller). For ages, flagella have been generally regarded as important virulence factors, mainly because of their motility property. However, flagella are getting recognized to play multiple roles with more functions besides motility and chemotaxis. Recent evidence has pinpointed that the bacterial flagella participate in many additional processes including adhesion, biofilm formation, virulence factor secretion, and modulation of the immune system of eukaryotic cells. This mini-review summarizes data from recent studies that elucidated how flagella, as a virulence factor, contribute to bacterial pathogenicity.

  9. Gram-negative and Gram-positive bacterial extracellular vesicles.

    PubMed

    Kim, Ji Hyun; Lee, Jaewook; Park, Jaesung; Gho, Yong Song

    2015-04-01

    Like mammalian cells, Gram-negative and Gram-positive bacteria release nano-sized membrane vesicles into the extracellular environment either in a constitutive manner or in a regulated manner. These bacterial extracellular vesicles are spherical bilayered proteolipids enriched with bioactive proteins, lipids, nucleic acids, and virulence factors. Recent progress in this field supports the critical pathophysiological functions of these vesicles in both bacteria-bacteria and bacteria-host interactions. This review provides an overview of the current understanding on Gram-negative and Gram-positive bacterial extracellular vesicles, especially regarding the biogenesis, components, and functions in poly-species communities. We hope that this review will stimulate additional research in this emerging field of bacterial extracellular vesicles and contribute to the development of extracellular vesicle-based diagnostic tools and effective vaccines against pathogenic Gram-negative and Gram-positive bacteria.

  10. Pathogenicity Islands in Bacterial Pathogenesis

    PubMed Central

    Schmidt, Herbert; Hensel, Michael

    2004-01-01

    In this review, we focus on a group of mobile genetic elements designated pathogenicity islands (PAI). These elements play a pivotal role in the virulence of bacterial pathogens of humans and are also essential for virulence in pathogens of animals and plants. Characteristic molecular features of PAI of important human pathogens and their role in pathogenesis are described. The availability of a large number of genome sequences of pathogenic bacteria and their benign relatives currently offers a unique opportunity for the identification of novel pathogen-specific genomic islands. However, this knowledge has to be complemented by improved model systems for the analysis of virulence functions of bacterial pathogens. PAI apparently have been acquired during the speciation of pathogens from their nonpathogenic or environmental ancestors. The acquisition of PAI not only is an ancient evolutionary event that led to the appearance of bacterial pathogens on a timescale of millions of years but also may represent a mechanism that contributes to the appearance of new pathogens within a human life span. The acquisition of knowledge about PAI, their structure, their mobility, and the pathogenicity factors they encode not only is helpful in gaining a better understanding of bacterial evolution and interactions of pathogens with eukaryotic host cells but also may have important practical implications such as providing delivery systems for vaccination, tools for cell biology, and tools for the development of new strategies for therapy of bacterial infections. PMID:14726454

  11. Lifestyles of the effector-rich: genome-enabled characterization of bacterial plant pathogens

    USDA-ARS?s Scientific Manuscript database

    Genome sequencing of bacterial plant pathogens is providing transformative insights into the complex network of molecular plant-microbe interactions mediated by extracellular effectors during pathogenesis. Bacterial pathogens sequenced to completion are phylogenetically diverse and vary significant...

  12. Host Specificity of Bacterial Pathogens

    PubMed Central

    Bäumler, Andreas; Fang, Ferric C.

    2013-01-01

    Most pathogens are able to infect multiple hosts but some are highly adapted to a single-host species. A detailed understanding of the basis of host specificity can provide important insights into molecular pathogenesis, the evolution of pathogenic microbes, and the potential for pathogens to cross the species barrier to infect new hosts. Comparative genomics and the development of humanized mouse models have provided important new tools with which to explore the basis of generalism and specialism. This review will examine host specificity of bacterial pathogens with a focus on generalist and specialist serovars of Salmonella enterica. PMID:24296346

  13. Taxonomy of bacterial fish pathogens.

    PubMed

    Austin, Brian

    2011-02-02

    Bacterial taxonomy has progressed from reliance on highly artificial culture-dependent techniques involving the study of phenotype (including morphological, biochemical and physiological data) to the modern applications of molecular biology, most recently 16S rRNA gene sequencing, which gives an insight into evolutionary pathways (= phylogenetics). The latter is applicable to culture-independent approaches, and has led directly to the recognition of new uncultured bacterial groups, i.e. "Candidatus", which have been associated as the cause of some fish diseases, including rainbow trout summer enteritic syndrome. One immediate benefit is that 16S rRNA gene sequencing has led to increased confidence in the accuracy of names allocated to bacterial pathogens. This is in marked contrast to the previous dominance of phenotyping, and identifications, which have been subsequently challenged in the light of 16S rRNA gene sequencing. To date, there has been some fluidity over the names of bacterial fish pathogens, with some, for example Vibrio anguillarum, being divided into two separate entities (V. anguillarum and V. ordalii). Others have been combined, for example V. carchariae, V. harveyi and V. trachuri as V. harveyi. Confusion may result with some organisms recognized by more than one name; V. anguillarum was reclassified as Beneckea and Listonella, with Vibrio and Listonella persisting in the scientific literature. Notwithstanding, modern methods have permitted real progress in the understanding of the taxonomic relationships of many bacterial fish pathogens.

  14. Taxonomy of bacterial fish pathogens

    PubMed Central

    2011-01-01

    Bacterial taxonomy has progressed from reliance on highly artificial culture-dependent techniques involving the study of phenotype (including morphological, biochemical and physiological data) to the modern applications of molecular biology, most recently 16S rRNA gene sequencing, which gives an insight into evolutionary pathways (= phylogenetics). The latter is applicable to culture-independent approaches, and has led directly to the recognition of new uncultured bacterial groups, i.e. "Candidatus", which have been associated as the cause of some fish diseases, including rainbow trout summer enteritic syndrome. One immediate benefit is that 16S rRNA gene sequencing has led to increased confidence in the accuracy of names allocated to bacterial pathogens. This is in marked contrast to the previous dominance of phenotyping, and identifications, which have been subsequently challenged in the light of 16S rRNA gene sequencing. To date, there has been some fluidity over the names of bacterial fish pathogens, with some, for example Vibrio anguillarum, being divided into two separate entities (V. anguillarum and V. ordalii). Others have been combined, for example V. carchariae, V. harveyi and V. trachuri as V. harveyi. Confusion may result with some organisms recognized by more than one name; V. anguillarum was reclassified as Beneckea and Listonella, with Vibrio and Listonella persisting in the scientific literature. Notwithstanding, modern methods have permitted real progress in the understanding of the taxonomic relationships of many bacterial fish pathogens. PMID:21314902

  15. Novel Anti-bacterial Activities of β-defensin 1 in Human Platelets: Suppression of Pathogen Growth and Signaling of Neutrophil Extracellular Trap Formation

    PubMed Central

    Schwertz, Hansjörg; Cody, Mark J.; Franks, Zechariah; Tolley, Neal D.; Kahr, Walter H. A.; Lindemann, Stephan; Seizer, Peter; Yost, Christian C.; Zimmerman, Guy A.

    2011-01-01

    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. PMID:22102811

  16. Hydrogen peroxide generation by the pepper extracellular peroxidase CaPO2 activates local and systemic cell death and defense response to bacterial pathogens.

    PubMed

    Choi, Hyong Woo; Kim, Young Jin; Lee, Sung Chul; Hong, Jeum Kyu; Hwang, Byung Kook

    2007-11-01

    Reactive oxygen species (ROS) are responsible for mediating cellular defense responses in plants. Controversy has existed over the origin of ROS in plant defense. We have isolated a novel extracellular peroxidase gene, CaPO2, from pepper (Capsicum annuum). Local or systemic expression of CaPO2 is induced in pepper by avirulent Xanthomonas campestris pv vesicatoria (Xcv) infection. We examined the function of the CaPO2 gene in plant defense using the virus-induced gene silencing technique and gain-of-function transgenic plants. CaPO2-silenced pepper plants were highly susceptible to Xcv infection. Virus-induced gene silencing of the CaPO2 gene also compromised hydrogen peroxide (H(2)O(2)) accumulation and hypersensitive cell death in leaves, both locally and systemically, during avirulent Xcv infection. In contrast, overexpression of CaPO2 in Arabidopsis (Arabidopsis thaliana) conferred enhanced disease resistance accompanied by cell death, H(2)O(2) accumulation, and PR gene induction. In CaPO2-overexpression Arabidopsis leaves infected by Pseudomonas syringae pv tomato, H(2)O(2) generation was sensitive to potassium cyanide (a peroxidase inhibitor) but insensitive to diphenylene iodonium (an NADPH oxidase inhibitor), suggesting that H(2)O(2) generation depends on peroxidase in Arabidopsis. Together, these results indicate that the CaPO2 peroxidase is involved in ROS generation, both locally and systemically, to activate cell death and PR gene induction during the defense response to pathogen invasion.

  17. Hydrogen Peroxide Generation by the Pepper Extracellular Peroxidase CaPO2 Activates Local and Systemic Cell Death and Defense Response to Bacterial Pathogens1[W][OA

    PubMed Central

    Choi, Hyong Woo; Kim, Young Jin; Lee, Sung Chul; Hong, Jeum Kyu; Hwang, Byung Kook

    2007-01-01

    Reactive oxygen species (ROS) are responsible for mediating cellular defense responses in plants. Controversy has existed over the origin of ROS in plant defense. We have isolated a novel extracellular peroxidase gene, CaPO2, from pepper (Capsicum annuum). Local or systemic expression of CaPO2 is induced in pepper by avirulent Xanthomonas campestris pv vesicatoria (Xcv) infection. We examined the function of the CaPO2 gene in plant defense using the virus-induced gene silencing technique and gain-of-function transgenic plants. CaPO2-silenced pepper plants were highly susceptible to Xcv infection. Virus-induced gene silencing of the CaPO2 gene also compromised hydrogen peroxide (H2O2) accumulation and hypersensitive cell death in leaves, both locally and systemically, during avirulent Xcv infection. In contrast, overexpression of CaPO2 in Arabidopsis (Arabidopsis thaliana) conferred enhanced disease resistance accompanied by cell death, H2O2 accumulation, and PR gene induction. In CaPO2-overexpression Arabidopsis leaves infected by Pseudomonas syringae pv tomato, H2O2 generation was sensitive to potassium cyanide (a peroxidase inhibitor) but insensitive to diphenylene iodonium (an NADPH oxidase inhibitor), suggesting that H2O2 generation depends on peroxidase in Arabidopsis. Together, these results indicate that the CaPO2 peroxidase is involved in ROS generation, both locally and systemically, to activate cell death and PR gene induction during the defense response to pathogen invasion. PMID:17905862

  18. Bacterial Toxins as Pathogen Weapons Against Phagocytes

    PubMed Central

    do Vale, Ana; Cabanes, Didier; Sousa, Sandra

    2016-01-01

    Bacterial toxins are virulence factors that manipulate host cell functions and take over the control of vital processes of living organisms to favor microbial infection. Some toxins directly target innate immune cells, thereby annihilating a major branch of the host immune response. In this review we will focus on bacterial toxins that act from the extracellular milieu and hinder the function of macrophages and neutrophils. In particular, we will concentrate on toxins from Gram-positive and Gram-negative bacteria that manipulate cell signaling or induce cell death by either imposing direct damage to the host cells cytoplasmic membrane or enzymatically modifying key eukaryotic targets. Outcomes regarding pathogen dissemination, host damage and disease progression will be discussed. PMID:26870008

  19. Bacterial Toxins as Pathogen Weapons Against Phagocytes.

    PubMed

    do Vale, Ana; Cabanes, Didier; Sousa, Sandra

    2016-01-01

    Bacterial toxins are virulence factors that manipulate host cell functions and take over the control of vital processes of living organisms to favor microbial infection. Some toxins directly target innate immune cells, thereby annihilating a major branch of the host immune response. In this review we will focus on bacterial toxins that act from the extracellular milieu and hinder the function of macrophages and neutrophils. In particular, we will concentrate on toxins from Gram-positive and Gram-negative bacteria that manipulate cell signaling or induce cell death by either imposing direct damage to the host cells cytoplasmic membrane or enzymatically modifying key eukaryotic targets. Outcomes regarding pathogen dissemination, host damage and disease progression will be discussed.

  20. How old are bacterial pathogens?

    PubMed Central

    2016-01-01

    Only few molecular studies have addressed the age of bacterial pathogens that infected humans before the beginnings of medical bacteriology, but these have provided dramatic insights. The global genetic diversity of Helicobacter pylori, which infects human stomachs, parallels that of its human host. The time to the most recent common ancestor (tMRCA) of these bacteria approximates that of anatomically modern humans, i.e. at least 100 000 years, after calibrating the evolutionary divergence within H. pylori against major ancient human migrations. Similarly, genomic reconstructions of Mycobacterium tuberculosis, the cause of tuberculosis, from ancient skeletons in South America and mummies in Hungary support estimates of less than 6000 years for the tMRCA of M. tuberculosis. Finally, modern global patterns of genetic diversity and ancient DNA studies indicate that during the last 5000 years plague caused by Yersinia pestis has spread globally on multiple occasions from China and Central Asia. Such tMRCA estimates provide only lower bounds on the ages of bacterial pathogens, and additional studies are needed for realistic upper bounds on how long humans and animals have suffered from bacterial diseases. PMID:27534956

  1. Mycobacterium massiliense Induces Macrophage Extracellular Traps with Facilitating Bacterial Growth

    PubMed Central

    Yoon, Yina; Na, Yirang; Kim, Bum-Joon; Seok, Seung Hyeok

    2016-01-01

    Human neutrophils have been known to release neutrophil extracellular traps (NETs), antimicrobial DNA structures capable of capturing and killing microbes. Recently, a similar phenomenon has been reported in macrophages infected with various pathogens. However, a role for macrophages extracellular traps (METs) in host defense responses against Mycobacterium massiliense (M. mass) has yet to be described. In this study, we show that M. mass, a rapid growing mycobacterium (RGM), also induces the release of METs from PMA-differentiated THP-1 cells. Intriguingly, this process is not dependent on NADPH oxidase activity, which regulates NET formation. Instead, M. mass-induced MET formation partially depends on calcium influx and requires phagocytosis of high bacterial load. The METs consist of a DNA backbone embedded with microbicidal proteins such as histone, MPO and elastase. Released METs entrap M. mass and prevent their dissemination, but do not have bactericidal activity. Instead, they result in enhanced bacterial growth. In this regard, METs were considered to provide interaction of M. mass with cells and an environment for bacterial aggregation, which may facilitate mycobacterial survival and growth. In conclusion, our results demonstrate METs as an innate defense response against M. mass infection, and suggest that extracellular traps play a multifaceted role in the interplay between host and bacteria. PMID:27191593

  2. Mycobacterium massiliense Induces Macrophage Extracellular Traps with Facilitating Bacterial Growth.

    PubMed

    Je, Sungmo; Quan, Hailian; Yoon, Yina; Na, Yirang; Kim, Bum-Joon; Seok, Seung Hyeok

    2016-01-01

    Human neutrophils have been known to release neutrophil extracellular traps (NETs), antimicrobial DNA structures capable of capturing and killing microbes. Recently, a similar phenomenon has been reported in macrophages infected with various pathogens. However, a role for macrophages extracellular traps (METs) in host defense responses against Mycobacterium massiliense (M. mass) has yet to be described. In this study, we show that M. mass, a rapid growing mycobacterium (RGM), also induces the release of METs from PMA-differentiated THP-1 cells. Intriguingly, this process is not dependent on NADPH oxidase activity, which regulates NET formation. Instead, M. mass-induced MET formation partially depends on calcium influx and requires phagocytosis of high bacterial load. The METs consist of a DNA backbone embedded with microbicidal proteins such as histone, MPO and elastase. Released METs entrap M. mass and prevent their dissemination, but do not have bactericidal activity. Instead, they result in enhanced bacterial growth. In this regard, METs were considered to provide interaction of M. mass with cells and an environment for bacterial aggregation, which may facilitate mycobacterial survival and growth. In conclusion, our results demonstrate METs as an innate defense response against M. mass infection, and suggest that extracellular traps play a multifaceted role in the interplay between host and bacteria.

  3. Plant innate immunity against human bacterial pathogens

    PubMed Central

    Melotto, Maeli; Panchal, Shweta; Roy, Debanjana

    2014-01-01

    Certain human bacterial pathogens such as the enterohemorrhagic Escherichia coli and Salmonella enterica are not proven to be plant pathogens yet. Nonetheless, under certain conditions they can survive on, penetrate into, and colonize internal plant tissues causing serious food borne disease outbreaks. In this review, we highlight current understanding on the molecular mechanisms of plant responses against human bacterial pathogens and discuss salient common and contrasting themes of plant interactions with phytopathogens or human pathogens. PMID:25157245

  4. Escaping Underground Nets: Extracellular DNases Degrade Plant Extracellular Traps and Contribute to Virulence of the Plant Pathogenic Bacterium Ralstonia solanacearum

    PubMed Central

    Tran, Tuan Minh; MacIntyre, April; Hawes, Martha; Allen, Caitilyn

    2016-01-01

    Plant root border cells have been recently recognized as an important physical defense against soil-borne pathogens. Root border cells produce an extracellular matrix of protein, polysaccharide and DNA that functions like animal neutrophil extracellular traps to immobilize pathogens. Exposing pea root border cells to the root-infecting bacterial wilt pathogen Ralstonia solanacearum triggered release of DNA-containing extracellular traps in a flagellin-dependent manner. These traps rapidly immobilized the pathogen and killed some cells, but most of the entangled bacteria eventually escaped. The R. solanacearum genome encodes two putative extracellular DNases (exDNases) that are expressed during pathogenesis, suggesting that these exDNases contribute to bacterial virulence by enabling the bacterium to degrade and escape root border cell traps. We tested this hypothesis with R. solanacearum deletion mutants lacking one or both of these nucleases, named NucA and NucB. Functional studies with purified proteins revealed that NucA and NucB are non-specific endonucleases and that NucA is membrane-associated and cation-dependent. Single ΔnucA and ΔnucB mutants and the ΔnucA/B double mutant all had reduced virulence on wilt-susceptible tomato plants in a naturalistic soil-soak inoculation assay. The ΔnucA/B mutant was out-competed by the wild-type strain in planta and was less able to stunt root growth or colonize plant stems. Further, the double nuclease mutant could not escape from root border cells in vitro and was defective in attachment to pea roots. Taken together, these results demonstrate that extracellular DNases are novel virulence factors that help R. solanacearum successfully overcome plant defenses to infect plant roots and cause bacterial wilt disease. PMID:27336156

  5. Escaping Underground Nets: Extracellular DNases Degrade Plant Extracellular Traps and Contribute to Virulence of the Plant Pathogenic Bacterium Ralstonia solanacearum.

    PubMed

    Tran, Tuan Minh; MacIntyre, April; Hawes, Martha; Allen, Caitilyn

    2016-06-01

    Plant root border cells have been recently recognized as an important physical defense against soil-borne pathogens. Root border cells produce an extracellular matrix of protein, polysaccharide and DNA that functions like animal neutrophil extracellular traps to immobilize pathogens. Exposing pea root border cells to the root-infecting bacterial wilt pathogen Ralstonia solanacearum triggered release of DNA-containing extracellular traps in a flagellin-dependent manner. These traps rapidly immobilized the pathogen and killed some cells, but most of the entangled bacteria eventually escaped. The R. solanacearum genome encodes two putative extracellular DNases (exDNases) that are expressed during pathogenesis, suggesting that these exDNases contribute to bacterial virulence by enabling the bacterium to degrade and escape root border cell traps. We tested this hypothesis with R. solanacearum deletion mutants lacking one or both of these nucleases, named NucA and NucB. Functional studies with purified proteins revealed that NucA and NucB are non-specific endonucleases and that NucA is membrane-associated and cation-dependent. Single ΔnucA and ΔnucB mutants and the ΔnucA/B double mutant all had reduced virulence on wilt-susceptible tomato plants in a naturalistic soil-soak inoculation assay. The ΔnucA/B mutant was out-competed by the wild-type strain in planta and was less able to stunt root growth or colonize plant stems. Further, the double nuclease mutant could not escape from root border cells in vitro and was defective in attachment to pea roots. Taken together, these results demonstrate that extracellular DNases are novel virulence factors that help R. solanacearum successfully overcome plant defenses to infect plant roots and cause bacterial wilt disease.

  6. Dual function of a bacterial protein as an adhesin and extracellular effector of host GTPase signaling

    PubMed Central

    Stones, Daniel Henry; Krachler, Anne Marie

    2015-01-01

    Bacterial pathogens often target conserved cellular mechanisms within their hosts to rewire signaling pathways and facilitate infection. Rho GTPases are important nodes within eukaryotic signaling networks and thus constitute a common target of pathogen-mediated manipulation. A diverse array of microbial mechanisms exists to interfere with Rho GTPase signaling. While targeting of GTPases by secreted bacterial effectors is a well-known strategy bacterial pathogens employ to interfere with the host, we have recently described pathogen adhesion as a novel extracellular stimulus that hijacks host GTPase signaling. The Multivalent Adhesion Molecule MAM7 from Vibrio parahaemolyticus directly binds host cell membrane lipids. The ensuing coalescence of phosphatidic acid ligands in the host membrane leads to downstream activation of RhoA and actin rearrangements. Herein, we discuss mechanistic models of lipid-mediated Rho activation and the implications from the infected host's and the pathogen's perspective. PMID:26156628

  7. Heme Synthesis and Acquisition in Bacterial Pathogens

    PubMed Central

    Choby, Jacob E.; Skaar, Eric P.

    2016-01-01

    Bacterial pathogens require the iron-containing cofactor heme to cause disease. Heme is essential to the function of hemoproteins, which are involved in energy generation by the electron transport chain, detoxification of host immune effectors, and other processes. During infection, bacterial pathogens must synthesize heme or acquire heme from the host; however, host heme is sequestered in high-affinity hemoproteins. Pathogens have evolved elaborate strategies to acquire heme from host sources, particularly hemoglobin, and both heme acquisition and synthesis are important for pathogenesis. Paradoxically, excess heme is toxic to bacteria and pathogens must rely on heme detoxification strategies. Heme is a key nutrient in the struggle for survival between host and pathogen, and its study has offered significant insight into the molecular mechanisms of bacterial pathogenesis. PMID:27019298

  8. Genome degeneration affects both extracellular and intracellular bacterial endosymbionts

    PubMed Central

    Feldhaar, Heike; Gross, Roy

    2009-01-01

    The obligate intracellular bacterial endosymbionts of insects are a paradigm for reductive genome evolution. A study published recently in BMC Biology demonstrates that similar evolutionary forces shaping genome structure may also apply to extracellular endosymbionts. PMID:19435469

  9. Use of Bacteriophages to control bacterial pathogens

    USDA-ARS?s Scientific Manuscript database

    Lytic bacteriophages can provide a natural method and an effective alternative to antibiotics to reduce bacterial pathogens in animals, foods, and other environments. Bacteriophages (phages) are viruses which infect bacterial cells and eventually kill them through lysis, and represent the most abun...

  10. Proteomics of Foodborne Bacterial Pathogens

    NASA Astrophysics Data System (ADS)

    Fagerquist, Clifton K.

    This chapter is intended to be a relatively brief overview of proteomic techniques currently in use for the identification and analysis of microorganisms with a special emphasis on foodborne pathogens. The chapter is organized as follows. First, proteomic techniques are introduced and discussed. Second, proteomic applications are presented specifically as they relate to the identification and qualitative/quantitative analysis of foodborne pathogens.

  11. Chronic Bacterial Pathogens: Mechanisms of Persistence

    PubMed Central

    Byndloss, Mariana X.; Tsolis, Renee M

    2015-01-01

    Summary Many bacterial pathogens can cause acute infections that are cleared with onset of adaptive immunity, however a subset of these pathogens can establish persistent, and sometimes lifelong infections. While bacteria causing chronic infections are phylogenetically diverse, they share common features in their interactions with the host that enable a protracted period of colonization. This chapter will compare the persistence strategies of two chronic pathogens from the Proteobacteria, Brucella abortus, and Salmonella enterica serovar Typhi (S. Typhi) to consider how these two pathogens, which are very different at the genomic level, can utilize common strategies to evade immune clearance to cause chronic intracellular infections of the mononuclear phagocyte system. PMID:27227304

  12. The social behaviours of bacterial pathogens.

    PubMed

    Popat, Roman; Crusz, Shanika A; Diggle, Stephen P

    2008-01-01

    The term quorum sensing (QS) is used to describe communication between bacterial cells, whereby a coordinated population response is controlled by diffusible signal molecules produced by individuals. Studies on QS-mediated signalling processes in bacteria have revealed the existence of intricate regulatory networks to enable bacterial populations to fine tune their responses to environmental changes and increase their chances of survival, using complex signalling pathways. A population of bacteria invading a host may benefit from the coordinated release of virulence determinants and in vitro studies have shown that QS regulates virulence factor production in many species of bacteria. However, the role of QS in vivo is less well understood, but has been demonstrated to be important in several pathogenic organisms. There is a growing interest in blocking bacterial cell-cell communication as a means to control infections. This review discusses QS from a pathogenic perspective and discusses the potential of QS as an anti-pathogenic target.

  13. Molecular Mechanisms of Bacterial Pathogenicity

    NASA Astrophysics Data System (ADS)

    Fuchs, Thilo Martin

    Cautious optimism has arisen over recent decades with respect to the long struggle against bacteria, viruses, and parasites. This has been offset, however, by a fatal complacency stemming from previous successes such as the development of antimicrobial drugs, the eradication of smallpox, and global immunization programs. Infectious diseases nevertheless remain the world's leading cause of death, killing at least 17 million persons annually [61]. Diarrheal diseases caused by Vibrio cholerae or Shigella dysenteriae kill about 3 million persons every year, most of them young children: Another 4 million die of tuberculosis or tetanus. Outbreaks of diphtheria in Eastern Europe threatens the population with a disease that had previously seemed to be overcome. Efforts to control infectious diseases more comprehensively are undermined not only by socioeconomic conditions but also by the nature of the pathogenic organisms itself; some isolates of Staphylococcus aureus and Enterobacter have become so resistant to drugs by horizontal gene transfer that they are almost untreatable. In addition, the mechanism of genetic variability helps pathogens to evade the human immune system, thus compromising the development of powerful vaccines. Therefore detailed knowledge of the molecular mechanisms of microbial pathogenicity is absolutely necessary to develop new strategies against infectious diseases and thus to lower their impact on human health and social development.

  14. Classical Labeling of Bacterial Pathogens According to Their Lifestyle in the Host: Inconsistencies and Alternatives

    PubMed Central

    Silva, Manuel T.

    2012-01-01

    An ample understanding of the complex interactions between host and pathogen will improve our ability to develop new prophylactic and therapeutic measures against infection. Precise classification of infectious agents in regards to their infective lifestyles in the host and corresponding pathogenic implications are required because clear concepts are essential to plan fruitful research. Classically, pathogenic bacteria are classified as extracellular, facultative intracellular, and obligate intracellular. In my opinion, this classification is inadequate because, as concluded from data here discussed, it is based on inconsistencies and hyper-valorizes the capacity of the infectious agent replicate in vitro in cell-free media. For a microbial pathogen, what matters is whether intra- or extracellularity is in the context of the in vivo life and in association with pathogenicity. When living as a pathogen in association with its host, what is relevant in microbiological terms is not the ability to grow in artificial cell-free bacteriological media or in environmental niches but whether the intracellular infectious agent, besides the phase of intracellular growth which is behind its label, also is able to live extracellularly in the natural settings of the extracellular territories of their hosts. To eliminate the inconsistencies associated with the classical labeling of bacterial pathogens, I propose that bacterial pathogens be labeled exclusive extracellular, dual intracellular/extracellular and exclusive intracellular based on their infective lifestyle in the host, not in the ability to grow in artificial bacteriological media. PMID:22393329

  15. Catabolism of host-derived compounds during extracellular bacterial infections.

    PubMed

    Meadows, Jamie A; Wargo, Matthew J

    2014-02-01

    Efficient catabolism of host-derived compounds is essential for bacterial survival and virulence. While these links in intracellular bacteria are well studied, such studies in extracellular bacteria lag behind, mostly for technical reasons. The field has identified important metabolic pathways, but the mechanisms by which they impact infection and in particular, establishing the importance of a compound's catabolism versus alternate metabolic roles has been difficult. In this review we will examine evidence for catabolism during extracellular bacterial infections in animals and known or potential roles in virulence. In the process, we point out key gaps in the field that will require new or newly adapted techniques. © 2013 Wiley Periodicals, Inc.

  16. Catabolism of host-derived compounds during extracellular bacterial infections

    PubMed Central

    Meadows, Jamie A.; Wargo, Matthew J.

    2014-01-01

    Efficient catabolism of host-derived compounds is essential for bacterial survival and virulence. While these links in intracellular bacteria are well-studied, such studies in extracellular bacteria lag behind, mostly for technical reasons. The field has identified important metabolic pathways, but the mechanisms by which they impact infection and in particular, establishing the importance of a compound’s catabolism versus alternate metabolic roles has been difficult. In this review we will examine evidence for catabolism during extracellular bacterial infections in animals and known or potential roles in virulence. In the process, we point out key gaps in the field that will require new or newly adapted techniques. PMID:24038340

  17. Within-host evolution of bacterial pathogens

    PubMed Central

    Didelot, Xavier; Walker, A. Sarah; Peto, Tim E.; Crook, Derrick W.; Wilson, Daniel J.

    2016-01-01

    Whole genome sequencing has opened the way to investigating the dynamics and genomic evolution of bacterial pathogens during colonization and infection of humans. The application of this technology to the longitudinal study of adaptation in the infected host — in particular, the evolution of drug resistance and host adaptation in patients chronically infected with opportunistic pathogens — has revealed remarkable patterns of convergent evolution, pointing to an inherent repeatability of evolution. In this Review, we describe how these studies have advanced our understanding of the mechanisms and principles of within-host genome evolution, and we consider the consequences of findings such as a potent adaptive potential for pathogenicity. Finally, we discuss the possibility that genomics may be used in the future to predict the clinical progression of bacterial infections, and to suggest the best treatment option. PMID:26806595

  18. Exploiting Quorum Sensing To Confuse Bacterial Pathogens

    PubMed Central

    LaSarre, Breah

    2013-01-01

    SUMMARY Cell-cell communication, or quorum sensing, is a widespread phenomenon in bacteria that is used to coordinate gene expression among local populations. Its use by bacterial pathogens to regulate genes that promote invasion, defense, and spread has been particularly well documented. With the ongoing emergence of antibiotic-resistant pathogens, there is a current need for development of alternative therapeutic strategies. An antivirulence approach by which quorum sensing is impeded has caught on as a viable means to manipulate bacterial processes, especially pathogenic traits that are harmful to human and animal health and agricultural productivity. The identification and development of chemical compounds and enzymes that facilitate quorum-sensing inhibition (QSI) by targeting signaling molecules, signal biogenesis, or signal detection are reviewed here. Overall, the evidence suggests that QSI therapy may be efficacious against some, but not necessarily all, bacterial pathogens, and several failures and ongoing concerns that may steer future studies in productive directions are discussed. Nevertheless, various QSI successes have rightfully perpetuated excitement surrounding new potential therapies, and this review highlights promising QSI leads in disrupting pathogenesis in both plants and animals. PMID:23471618

  19. Interaction of Bacterial Exotoxins with Neutrophil Extracellular Traps: Impact for the Infected Host

    PubMed Central

    von Köckritz-Blickwede, Maren; Blodkamp, Stefanie; Nizet, Victor

    2016-01-01

    Since their discovery in 2004, neutrophil extracellular traps (NETs) have been characterized as a fundamental host innate immune defense against various pathogens. Released in response to infectious and pro-inflammatory stimuli, NETs can immobilize invading pathogens within a fibrous matrix consisting of DNA, histones, and antimicrobial peptides. Conversely, excessive or dysregulated NET release may hold a variety of detrimental consequences for the host. A fine balance between NET formation and elimination is necessary to sustain a protective effect during infectious challenge. In recent years, a number of microbial virulence factors have been shown to modulate formation of NETs, thereby facilitating colonization or spread within the host. In this mini-review we summarize the contemporary research on the interaction of bacterial exotoxins with neutrophils that modulate NET production, focusing particular attention on consequences for the host. Understanding host–pathogen dynamics in this extracellular battlefield of innate immunity may provide novel therapeutic approaches for infectious and inflammatory disorders. PMID:27064864

  20. Emerging bacterial pathogens: the past and beyond.

    PubMed

    Vouga, M; Greub, G

    2016-01-01

    Since the 1950s, medical communities have been facing with emerging and reemerging infectious diseases, and emerging pathogens are now considered to be a major microbiologic public health threat. In this review, we focus on bacterial emerging diseases and explore factors involved in their emergence as well as future challenges. We identified 26 major emerging and reemerging infectious diseases of bacterial origin; most of them originated either from an animal and are considered to be zoonoses or from water sources. Major contributing factors in the emergence of these bacterial infections are: (1) development of new diagnostic tools, such as improvements in culture methods, development of molecular techniques and implementation of mass spectrometry in microbiology; (2) increase in human exposure to bacterial pathogens as a result of sociodemographic and environmental changes; and (3) emergence of more virulent bacterial strains and opportunistic infections, especially affecting immunocompromised populations. A precise definition of their implications in human disease is challenging and requires the comprehensive integration of microbiological, clinical and epidemiologic aspects as well as the use of experimental models. It is now urgent to allocate financial resources to gather international data to provide a better understanding of the clinical relevance of these waterborne and zoonotic emerging diseases. Copyright © 2015. Published by Elsevier Ltd.

  1. Antibiotic resistance in ocular bacterial pathogens.

    PubMed

    Sharma, S

    2011-01-01

    Bacterial infections of the eye are common and ophthalmologists are spoilt for choice with a variety of antibiotics available in the market. Antibiotics can be administered in the eye by a number of routes; topical, subconjunctival, subtenon and intraocular. Apart from a gamut of eye drops available, ophthalmologists also have the option of preparing fortified eye drops from parenteral formulations, thereby, achieving high concentrations; often much above the minimum inhibitory concentration (MIC), of antibiotics in ocular tissues during therapy. Antibiotic resistance among ocular pathogens is increasing in parallel with the increase seen over the years in bacteria associated with systemic infections. Although it is believed that the rise in resistant ocular bacterial isolates is linked to the rise in resistant systemic pathogens, recent evidence has correlated the emergence of resistant bacteria in the eye to prior topical antibiotic therapy. One would like to believe that either of these contributes to the emergence of resistance to antibiotics among ocular pathogens. Until recently, ocular pathogens resistant to fluoroquinolones have been minimal but the pattern is currently alarming. The new 8-fluoroquinolone on the scene-besifloxacin, is developed exclusively for ophthalmic use and it is hoped that it will escape the selective pressure for resistance because of lack of systemic use. In addition to development of new antibacterial agents, the strategies to halt or control further development of resistant ocular pathogens should always include judicious use of antibiotics in the treatment of human, animal or plant diseases.

  2. Formaldehyde Stress Responses in Bacterial Pathogens

    PubMed Central

    Chen, Nathan H.; Djoko, Karrera Y.; Veyrier, Frédéric J.; McEwan, Alastair G.

    2016-01-01

    Formaldehyde is the simplest of all aldehydes and is highly cytotoxic. Its use and associated dangers from environmental exposure have been well documented. Detoxification systems for formaldehyde are found throughout the biological world and they are especially important in methylotrophic bacteria, which generate this compound as part of their metabolism of methanol. Formaldehyde metabolizing systems can be divided into those dependent upon pterin cofactors, sugar phosphates and those dependent upon glutathione. The more prevalent thiol-dependent formaldehyde detoxification system is found in many bacterial pathogens, almost all of which do not metabolize methane or methanol. This review describes the endogenous and exogenous sources of formaldehyde, its toxic effects and mechanisms of detoxification. The methods of formaldehyde sensing are also described with a focus on the formaldehyde responsive transcription factors HxlR, FrmR, and NmlR. Finally, the physiological relevance of detoxification systems for formaldehyde in bacterial pathogens is discussed. PMID:26973631

  3. Antimicrobial inflammasomes: unified signalling against diverse bacterial pathogens.

    PubMed

    Eldridge, Matthew J G; Shenoy, Avinash R

    2015-02-01

    Inflammasomes - molecular platforms for caspase-1 activation - have emerged as common hubs for a number of pathways that detect and respond to bacterial pathogens. Caspase-1 activation results in the secretion of bioactive IL-1β and IL-18 and pyroptosis, and thus launches a systemic immune and inflammatory response. In this review we discuss signal transduction leading to 'canonical' and 'non-canonical' activation of caspase-1 through the involvement of upstream caspases. Recent studies have identified a growing number of regulatory networks involving guanylate binding proteins, protein kinases, ubiquitylation and necroptosis related pathways that modulate inflammasome responses and immunity to bacterial infection. By being able to respond to extracellular, vacuolar and cytosolic bacteria, their cytosolic toxins or ligands for cell surface receptors, inflammasomes have emerged as important sentinels of infection.

  4. Microbiology: Detection of Bacterial Pathogens and Their Occurrence.

    ERIC Educational Resources Information Center

    Reasoner, Donald J.

    1978-01-01

    Presents a literature review of bacterial pathogens that are related to water pollution, covering publications from 1976-77. This review includes: (1) bacterial pathogens in animals; and (2) detection and identification of waterborne bacterial pathogens. A list of 129 references is also presented. (HM)

  5. [Extracellular proteases of mycelial fungi as participants of pathogenic processes].

    PubMed

    Dunaevskiĭ, Ia E; Matveeva, A R; Fatkhullina, G N; Beliakova, G A; Kolomiets, T M; Kovalenko, E D; Belozerskiĭ, M A

    2008-01-01

    The interest in proteases secreted by mycelial fungi is due to several reasons of which one of the most important is their involvement in the initiation and development of the pathogenic process. A comparison of saprophytic and phytopathogenic mycelial fungi revealed one characteristic feature, namely, the appearance of a new trypsin-like activity in phytopathogens that is absent in saprophytes. To clear up the question of whether the degree of pathogenicity of a fungus is related to the activity of secreted trypsin-like protease, several species of Fusarium of various pathogenicity were compared. In two species, F. sporotrichioides (which causes ear fusa-riosis of rye) and F. heterosporum (the causative agent of root rot in wheat), a clear correlation between the activity and pathogenicity was revealed: the more pathogenetic F. sporotrichioides exhibited a higher extracellular trypsin-like activity than the less pathogenetic species F. heterosporum. Thus, the presence of trypsin-like activity in a saprotroph-pathogen pair may be an indicator of the pathogenicity of a fungus; in some cases, the value of this activity may indicate the degree of its pathogenicity. This suggests that trypsin-like proteases specific to phytopathogens are directly involved in the pathogenetic process, probably, through interaction with the "sentry" protein or the product of the resistance gene.

  6. Extracellular Bacterial Proteases in Chronic Wounds: A Potential Therapeutic Target?

    PubMed

    Suleman, Louise

    2016-10-01

    Significance: Bacterial biofilms are considered to be responsible for over 80% of persistent infections, including chronic lung infections, osteomyelitis, periodontitis, endocarditis, and chronic wounds. Over 60% of chronic wounds are colonized with bacteria that reside within a biofilm. The exaggerated proteolytic environment of chronic wounds, more specifically elevated matrix metalloproteinases, is thought to be one of the possible reasons as to why chronic wounds fail to heal. However, the role of bacterial proteases within chronic wounds is not fully understood. Recent Advances: Recent research has shown that bacterial proteases can enable colonization and facilitate bacterial immune evasion. The inhibition of bacterial proteases such as Pseudomonas aeruginosa elastase B (LasB) has resulted in the disruption of the bacterial biofilm in vitro. P. aeruginosa is thought to be a key pathogen in chronic wound infection, and therefore, the disruption of these biofilms, potentially through the targeting of P. aeruginosa bacterial proteases, is an attractive therapeutic endeavor. Critical Issues: Disrupting biofilm formation through the inhibition of bacterial proteases may lead to the dissemination of bacteria from the biofilm, allowing planktonic cells to colonize new sites within the wound. Future Directions: Despite a plethora of evidence supporting the role of bacterial proteases as virulence factors in infection, there remains a distinct lack of research into the effect of bacterial proteases in chronic wounds. To assess the viability of targeting bacterial proteases, future research should aim to understand the role of these proteases in a variety of chronic wound subtypes.

  7. Genome dynamics in major bacterial pathogens

    PubMed Central

    Ambur, Ole Herman; Davidsen, Tonje; Frye, Stephan A; Balasingham, Seetha V; Lagesen, Karin; Rognes, Torbjørn; Tønjum, Tone

    2009-01-01

    Pathogenic bacteria continuously encounter multiple forms of stress in their hostile environments, which leads to DNA damage. With the new insight into biology offered by genome sequences, the elucidation of the gene content encoding proteins provides clues toward understanding the microbial lifestyle related to habitat and niche. Campylobacter jejuni, Haemophilus influenzae, Helicobacter pylori, Mycobacterium tuberculosis, the pathogenic Neisseria, Streptococcus pneumoniae, Streptococcus pyogenes and Staphylococcus aureus are major human pathogens causing detrimental morbidity and mortality at a global scale. An algorithm for the clustering of orthologs was established in order to identify whether orthologs of selected genes were present or absent in the genomes of the pathogenic bacteria under study. Based on the known genes for the various functions and their orthologs in selected pathogenic bacteria, an overview of the presence of the different types of genes was created. In this context, we focus on selected processes enabling genome dynamics in these particular pathogens, namely DNA repair, recombination and horizontal gene transfer. An understanding of the precise molecular functions of the enzymes participating in DNA metabolism and their importance in the maintenance of bacterial genome integrity has also, in recent years, indicated a future role for these enzymes as targets for therapeutic intervention. PMID:19396949

  8. Evasion of Neutrophil Extracellular Traps by Respiratory Pathogens.

    PubMed

    Storisteanu, Daniel M L; Pocock, Joanna M; Cowburn, Andrew S; Juss, Jatinder K; Nadesalingam, Angalee; Nizet, Victor; Chilvers, Edwin R

    2017-04-01

    The release of neutrophil extracellular traps (NETs) is a major immune mechanism intended to capture pathogens. These histone- and protease-coated DNA structures are released by neutrophils in response to a variety of stimuli, including respiratory pathogens, and have been identified in the airways of patients with respiratory infection, cystic fibrosis, acute lung injury, primary graft dysfunction, and chronic obstructive pulmonary disease. NET production has been demonstrated in the lungs of mice infected with Staphylococcus aureus, Klebsiella pneumoniae, and Aspergillus fumigatus. Since the discovery of NETs over a decade ago, evidence that "NET evasion" might act as an immune protection strategy among respiratory pathogens, including group A Streptococcus, Bordetella pertussis, and Haemophilus influenzae, has been growing, with the majority of these studies being published in the past 2 years. Evasion strategies fall into three main categories: inhibition of NET release by down-regulating host inflammatory responses; degradation of NETs using pathogen-derived DNases; and resistance to the microbicidal components of NETs, which involves a variety of mechanisms, including encapsulation. Hence, the evasion of NETs appears to be a widespread strategy to allow pathogen proliferation and dissemination, and is currently a topic of intense research interest. This article outlines the evidence supporting the three main strategies of NET evasion-inhibition, degradation, and resistance-with particular reference to common respiratory pathogens.

  9. Bacterial Pathogens Associated with Hidradenitis Suppurativa, France

    PubMed Central

    Coignard-Biehler, Hélène; Jais, Jean-Philippe; Quesne, Gilles; Frapy, Eric; Poirée, Sylvain; Le Guern, Anne-Sophie; Le Flèche-Matéos, Anne; Hovnanian, Alain; Consigny, Paul-Henry; Lortholary, Olivier; Nassif, Xavier; Nassif, Aude; Join-Lambert, Olivier

    2014-01-01

    Hidradenitis suppurativa (HS) is a skin disease characterized by recurrent nodules or abscesses and chronic suppurating lesions. In the absence of clear pathophysiology, HS is considered to be an inflammatory disease and has no satisfactory medical treatment. Recently, prolonged antimicrobial treatments were shown to improve or resolve HS lesions. We prospectively studied the microbiology of 102 HS lesions sampled from 82 patients using prolonged bacterial cultures and bacterial metagenomics on 6 samples. Staphylococcus lugdunensis was cultured as a unique or predominant isolate from 58% of HS nodules and abscesses, and a polymicrobial anaerobic microflora comprising strict anaerobes, milleri group streptococci, and actinomycetes was found in 24% of abscesses or nodules and in 87% of chronic suppurating lesions. These data show that bacteria known to cause soft tissue and skin infections are associated with HS lesions. Whether these pathogens are the cause of the lesions or are secondary infectious agents, these findings support targeted antimicrobial treatment of HS. PMID:25418454

  10. Extracellular DNases of Ralstonia solanacearum modulate biofilms and facilitate bacterial wilt virulence.

    PubMed

    Minh Tran, Tuan; MacIntyre, April; Khokhani, Devanshi; Hawes, Martha; Allen, Caitilyn

    2016-11-01

    Ralstonia solanacearum is a soil-borne vascular pathogen that colonizes plant xylem vessels, a flowing, low-nutrient habitat where biofilms could be adaptive. Ralstonia solanacearum forms biofilm in vitro, but it was not known if the pathogen benefits from biofilms during infection. Scanning electron microscopy revealed that during tomato infection, R. solanacearum forms biofilm-like masses in xylem vessels. These aggregates contain bacteria embedded in a matrix including chromatin-like fibres commonly observed in other bacterial biofilms. Chemical and enzymatic assays demonstrated that the bacterium releases extracellular DNA in culture and that DNA is an integral component of the biofilm matrix. An R. solanacearum mutant lacking the pathogen's two extracellular nucleases (exDNases) formed non-spreading colonies and abnormally thick biofilms in vitro. The biofilms formed by the exDNase mutant in planta contained more and thicker fibres. This mutant was also reduced in virulence on tomato plants and did not spread in tomato stems as well as the wild-type strain, suggesting that these exDNases facilitate biofilm maturation and bacterial dispersal. To our knowledge, this is the first demonstration that R. solanacearum forms biofilms in plant xylem vessels, and the first documentation that plant pathogens use DNases to modulate their biofilm structure for systemic spread and virulence. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

  11. Russian vaccines against especially dangerous bacterial pathogens

    PubMed Central

    Feodorova, Valentina A; Sayapina, Lidiya V; Corbel, Michael J; Motin, Vladimir L

    2014-01-01

    In response to the epidemiological situation, live attenuated or killed vaccines against anthrax, brucellosis, cholera, glanders, plague and tularemia were developed and used for immunization of at-risk populations in the Former Soviet Union. Certain of these vaccines have been updated and currently they are used on a selective basis, mainly for high risk occupations, in the Russian Federation. Except for anthrax and cholera these vaccines currently are the only licensed products available for protection against the most dangerous bacterial pathogens. Development of improved formulations and new products is ongoing. PMID:26038506

  12. A Macrophage Subversion Factor Is Shared by Intracellular and Extracellular Pathogens

    PubMed Central

    Laubier, Aurélie; Bleves, Sophie; Blanc-Potard, Anne-Béatrice

    2015-01-01

    Pathogenic bacteria have developed strategies to adapt to host environment and resist host immune response. Several intracellular bacterial pathogens, including Salmonella enterica and Mycobacterium tuberculosis, share the horizontally-acquired MgtC virulence factor that is important for multiplication inside macrophages. MgtC is also found in pathogenic Pseudomonas species. Here we investigate for the first time the role of MgtC in the virulence of an extracellular pathogen, Pseudomonas aeruginosa. A P. aeruginosa mgtC mutant is attenuated in the systemic infection model of zebrafish embryos, and strikingly, the attenuated phenotype is dependent on the presence of macrophages. In ex vivo experiments, the P. aeruginosa mgtC mutant is more sensitive to macrophage killing than the wild-type strain. However, wild-type and mutant strains behave similarly toward macrophage killing when macrophages are treated with an inhibitor of the vacuolar proton ATPase. Importantly, P. aeruginosa mgtC gene expression is strongly induced within macrophages and phagosome acidification contributes to an optimal expression of the gene. Thus, our results support the implication of a macrophage intracellular stage during P. aeruginosa acute infection and suggest that Pseudomonas MgtC requires phagosome acidification to play its intracellular role. Moreover, we demonstrate that P. aeruginosa MgtC is required for optimal growth in Mg2+ deprived medium, a property shared by MgtC factors from intracellular pathogens and, under Mg2+ limitation, P. aeruginosa MgtC prevents biofilm formation. We propose that MgtC shares a similar function in intracellular and extracellular pathogens, which contributes to macrophage resistance and fine-tune adaptation to host immune response in relation to the different bacterial lifestyles. In addition, the phenotypes observed with the mgtC mutant in infection models can be mimicked in wild-type P. aeruginosa strain by producing a MgtC antagonistic peptide, thus

  13. A Macrophage Subversion Factor Is Shared by Intracellular and Extracellular Pathogens.

    PubMed

    Belon, Claudine; Soscia, Chantal; Bernut, Audrey; Laubier, Aurélie; Bleves, Sophie; Blanc-Potard, Anne-Béatrice

    2015-06-01

    Pathogenic bacteria have developed strategies to adapt to host environment and resist host immune response. Several intracellular bacterial pathogens, including Salmonella enterica and Mycobacterium tuberculosis, share the horizontally-acquired MgtC virulence factor that is important for multiplication inside macrophages. MgtC is also found in pathogenic Pseudomonas species. Here we investigate for the first time the role of MgtC in the virulence of an extracellular pathogen, Pseudomonas aeruginosa. A P. aeruginosa mgtC mutant is attenuated in the systemic infection model of zebrafish embryos, and strikingly, the attenuated phenotype is dependent on the presence of macrophages. In ex vivo experiments, the P. aeruginosa mgtC mutant is more sensitive to macrophage killing than the wild-type strain. However, wild-type and mutant strains behave similarly toward macrophage killing when macrophages are treated with an inhibitor of the vacuolar proton ATPase. Importantly, P. aeruginosa mgtC gene expression is strongly induced within macrophages and phagosome acidification contributes to an optimal expression of the gene. Thus, our results support the implication of a macrophage intracellular stage during P. aeruginosa acute infection and suggest that Pseudomonas MgtC requires phagosome acidification to play its intracellular role. Moreover, we demonstrate that P. aeruginosa MgtC is required for optimal growth in Mg2+ deprived medium, a property shared by MgtC factors from intracellular pathogens and, under Mg2+ limitation, P. aeruginosa MgtC prevents biofilm formation. We propose that MgtC shares a similar function in intracellular and extracellular pathogens, which contributes to macrophage resistance and fine-tune adaptation to host immune response in relation to the different bacterial lifestyles. In addition, the phenotypes observed with the mgtC mutant in infection models can be mimicked in wild-type P. aeruginosa strain by producing a MgtC antagonistic peptide, thus

  14. Fluorogenic Substrate Detection of Viable Intracellular and Extracellular Pathogenic Protozoa

    NASA Astrophysics Data System (ADS)

    Jackson, Peter R.; Pappas, Michael G.; Hansen, Brian D.

    1985-01-01

    Viable Leishmania promastigotes and amastigotes were detected by epifluorescence microscopy with fluorescein diacetate being used to mark living parasites and the nucleic acid-binding compound ethidium bromide to stain dead cells. This procedure is superior to other assays because it is faster and detects viable intracellular as well as extracellular Leishmania. Furthermore, destruction of intracellular pathogens by macrophages is more accurately determined with fluorescein diacetate than with other stains. The procedure may have applications in programs to develop drugs and vaccines against protozoa responsible for human and animal disease.

  15. Poisons, ruffles and rockets: bacterial pathogens and the host cell cytoskeleton.

    PubMed

    Steele-Mortimer, O; Knodler, L A; Finlay, B B

    2000-02-01

    The cytoskeleton of eukaryotic cells is affected by a number of bacterial and viral pathogens. In this review we consider three recurring themes of cytoskeletal involvement in bacterial pathogenesis: 1) the effect of bacterial toxins on actin-regulating small GTP-binding proteins; 2) the invasion of non-phagocytic cells by the bacterial induction of ruffles at the plasma membrane; 3) the formation of actin tails and pedestals by intracellular and extracellular bacteria, respectively. Considerable progress has been made recently in the characterization of these processes. It is becoming clear that bacterial pathogens have developed a variety of sophisticated mechanisms for utilizing the complex cytoskeletal system of host cells. These bacterially-induced processes are now providing unique insights into the regulation of fundamental eukaryotic mechanisms.

  16. Water Microbiology. Bacterial Pathogens and Water

    PubMed Central

    Cabral, João P. S.

    2010-01-01

    Water is essential to life, but many people do not have access to clean and safe drinking water and many die of waterborne bacterial infections. In this review a general characterization of the most important bacterial diseases transmitted through water—cholera, typhoid fever and bacillary dysentery—is presented, focusing on the biology and ecology of the causal agents and on the diseases’ characteristics and their life cycles in the environment. The importance of pathogenic Escherichia coli strains and emerging pathogens in drinking water-transmitted diseases is also briefly discussed. Microbiological water analysis is mainly based on the concept of fecal indicator bacteria. The main bacteria present in human and animal feces (focusing on their behavior in their hosts and in the environment) and the most important fecal indicator bacteria are presented and discussed (focusing on the advantages and limitations of their use as markers). Important sources of bacterial fecal pollution of environmental waters are also briefly indicated. In the last topic it is discussed which indicators of fecal pollution should be used in current drinking water microbiological analysis. It was concluded that safe drinking water for all is one of the major challenges of the 21st century and that microbiological control of drinking water should be the norm everywhere. Routine basic microbiological analysis of drinking water should be carried out by assaying the presence of Escherichia coli by culture methods. Whenever financial resources are available, fecal coliform determinations should be complemented with the quantification of enterococci. More studies are needed in order to check if ammonia is reliable for a preliminary screening for emergency fecal pollution outbreaks. Financial resources should be devoted to a better understanding of the ecology and behavior of human and animal fecal bacteria in environmental waters. PMID:21139855

  17. Water microbiology. Bacterial pathogens and water.

    PubMed

    Cabral, João P S

    2010-10-01

    Water is essential to life, but many people do not have access to clean and safe drinking water and many die of waterborne bacterial infections. In this review a general characterization of the most important bacterial diseases transmitted through water-cholera, typhoid fever and bacillary dysentery-is presented, focusing on the biology and ecology of the causal agents and on the diseases' characteristics and their life cycles in the environment. The importance of pathogenic Escherichia coli strains and emerging pathogens in drinking water-transmitted diseases is also briefly discussed. Microbiological water analysis is mainly based on the concept of fecal indicator bacteria. The main bacteria present in human and animal feces (focusing on their behavior in their hosts and in the environment) and the most important fecal indicator bacteria are presented and discussed (focusing on the advantages and limitations of their use as markers). Important sources of bacterial fecal pollution of environmental waters are also briefly indicated. In the last topic it is discussed which indicators of fecal pollution should be used in current drinking water microbiological analysis. It was concluded that safe drinking water for all is one of the major challenges of the 21st century and that microbiological control of drinking water should be the norm everywhere. Routine basic microbiological analysis of drinking water should be carried out by assaying the presence of Escherichia coli by culture methods. Whenever financial resources are available, fecal coliform determinations should be complemented with the quantification of enterococci. More studies are needed in order to check if ammonia is reliable for a preliminary screening for emergency fecal pollution outbreaks. Financial resources should be devoted to a better understanding of the ecology and behavior of human and animal fecal bacteria in environmental waters.

  18. Pathogenic bacterial contaminations in hospital cafeteria foods.

    PubMed

    Rattanasena, Paweena; Somboonwatthanakul, Issaraporn

    2010-02-01

    This study aims to examine the pathogenic bacterial contaminations in foods sold in hospital cafeteria. A study was conducted between April and September of 2008 using cafeteria located in Mahasarakham provincial hospital, Thailand, as a study area. The cafeteria foods were evaluated for contaminations with Escherichia coli, Staphylococcus aureus, Salmonella typhimurium and Streptococcus faecalis, which have been earlier reported to cause nosocomial outbreaks. Of 33 different types of ready-to-eat foods, the majority (54.54%) were found to have bacteria >10(7) colony forming units per gram of food (cfu g(-1)), whereas 36.36% and only 9.10% of them were found to have bacteria at 10(6)-10(7) and <10(6) cfu g(-1), respectively. In addition, most of ready-to-eat foods were also shown to be contaminated with Escherichia coli (57.57%), followed by Streptococcus faecalis (51.51%), Staphylococcus aureus (48.48%) and Salmonella typhimurium (27.27%), respectively. In contrast, of 7 different types of freshly-made foods, the majority (71.42%) were found to have bacterial <10(6) cfu g(-1). Staphylococcus aureus was the most commonly found bacteria in freshly-made foods (42.85%), followed by Escherichia coli and Streptococcus faecalis at equal percentages (14.28%). None of the freshly-made foods were found to be contaminated with Streptococcus typhimurium. The results concluded that a number of ready-to-eat foods sold in the Mahasarakham hospital cafeteria were contaminated with several pathogenic bacteria at unacceptable levels. Healthcare authorities should be more aware that ready-to-eat cafeteria foods that are heavily contaminated with pathogenic bacteria may be harmful to healthcare workers and visitors and may result in nosocomial infections of the patients.

  19. Bacterial Genome Engineering and Synthetic Biology: Combating Pathogens

    DTIC Science & Technology

    2016-11-04

    Bacterial chromosomal modifications have greatly aided in better comprehension of bacterial mechanisms of pathogenesis and virulence. Among the genome...1 Bacterial Genome Engineering and Synthetic Biology: Combating Pathogens 1Malathy Krishnamurthy, 1Richard T. Moore, 1Sathish Rajamani, 1Rekha G...resistance in bacteria. Research The advent of new bacterial genome engineering and synthetic biology (SB) tools is providing promising diagnostic

  20. The Neglected Intrinsic Resistome of Bacterial Pathogens

    PubMed Central

    Fajardo, Alicia; Martínez-Martín, Nadia; Mercadillo, María; Galán, Juan C.; Ghysels, Bart; Matthijs, Sandra; Cornelis, Pierre; Wiehlmann, Lutz; Tümmler, Burkhard; Baquero, Fernando; Martínez, José L.

    2008-01-01

    Bacteria with intrinsic resistance to antibiotics are a worrisome health problem. It is widely believed that intrinsic antibiotic resistance of bacterial pathogens is mainly the consequence of cellular impermeability and activity of efflux pumps. However, the analysis of transposon-tagged Pseudomonas aeruginosa mutants presented in this article shows that this phenotype emerges from the action of numerous proteins from all functional categories. Mutations in some genes make P. aeruginosa more susceptible to antibiotics and thereby represent new targets. Mutations in other genes make P. aeruginosa more resistant and therefore define novel mechanisms for mutation-driven acquisition of antibiotic resistance, opening a new research field based in the prediction of resistance before it emerges in clinical environments. Antibiotics are not just weapons against bacterial competitors, but also natural signalling molecules. Our results demonstrate that antibiotic resistance genes are not merely protective shields and offer a more comprehensive view of the role of antibiotic resistance genes in the clinic and in nature. PMID:18286176

  1. Bacterial Extracellular Polysaccharides in Biofilm Formation and Function

    PubMed Central

    Limoli, Dominique H.; Jones, Christopher J.; Wozniak, Daniel J.

    2015-01-01

    Microbes produce a biofilm matrix consisting of proteins, extracellular DNA, and polysaccharides that is integral in the formation of bacterial communities. Historical studies of polysaccharides revealed that their overproduction often alters the colony morphology and can be diagnostic in identifying certain species. The polysaccharide component of the matrix can provide many diverse benefits to the cells in the biofilm, including adhesion, protection, and structure. Aggregative polysaccharides act as molecular glue, allowing the bacterial cells to adhere to each other as well as surfaces. Adhesion facilitates the colonization of both biotic and abiotic surfaces by allowing the bacteria to resist physical stresses imposed by fluid movement that could separate the cells from a nutrient source. Polysaccharides can also provide protection from a wide range of stresses, such as desiccation, immune effectors, and predators such as phagocytic cells and amoebae. Finally, polysaccharides can provide structure to biofilms, allowing stratification of the bacterial community and establishing gradients of nutrients and waste products. This can be advantageous for the bacteria by establishing a heterogeneous population that is prepared to endure stresses created by the rapidly changing environments that many bacteria encounter. The diverse range of polysaccharide structures, properties, and roles highlight the importance of this matrix constituent to the successful adaptation of bacteria to nearly every niche. Here, we present an overview of the current knowledge regarding the diversity and benefits that polysaccharide production provides to bacterial communities within biofilms. PMID:26185074

  2. Extracellular peptidases of the cereal pathogen Fusarium graminearum

    PubMed Central

    Lowe, Rohan G. T.; McCorkelle, Owen; Bleackley, Mark; Collins, Christine; Faou, Pierre; Mathivanan, Suresh; Anderson, Marilyn

    2015-01-01

    The plant pathogenic fungus Fusarium graminearum (Fgr) creates economic and health risks in cereals agriculture. Fgr causes head blight (or scab) of wheat and stalk rot of corn, reducing yield, degrading grain quality, and polluting downstream food products with mycotoxins. Fungal plant pathogens must secrete proteases to access nutrition and to breakdown the structural protein component of the plant cell wall. Research into the proteolytic activity of Fgr is hindered by the complex nature of the suite of proteases secreted. We used a systems biology approach comprising genome analysis, transcriptomics and label-free quantitative proteomics to characterize the peptidases deployed by Fgr during growth. A combined analysis of published microarray transcriptome datasets revealed seven transcriptional groupings of peptidases based on in vitro growth, in planta growth, and sporulation behaviors. A high resolution mass spectrometry-based proteomics analysis defined the extracellular proteases secreted by F. graminearum. A meta-classification based on sequence characters and transcriptional/translational activity in planta and in vitro provides a platform to develop control strategies that target Fgr peptidases. PMID:26635820

  3. Extracellular peptidases of the cereal pathogen Fusarium graminearum.

    PubMed

    Lowe, Rohan G T; McCorkelle, Owen; Bleackley, Mark; Collins, Christine; Faou, Pierre; Mathivanan, Suresh; Anderson, Marilyn

    2015-01-01

    The plant pathogenic fungus Fusarium graminearum (Fgr) creates economic and health risks in cereals agriculture. Fgr causes head blight (or scab) of wheat and stalk rot of corn, reducing yield, degrading grain quality, and polluting downstream food products with mycotoxins. Fungal plant pathogens must secrete proteases to access nutrition and to breakdown the structural protein component of the plant cell wall. Research into the proteolytic activity of Fgr is hindered by the complex nature of the suite of proteases secreted. We used a systems biology approach comprising genome analysis, transcriptomics and label-free quantitative proteomics to characterize the peptidases deployed by Fgr during growth. A combined analysis of published microarray transcriptome datasets revealed seven transcriptional groupings of peptidases based on in vitro growth, in planta growth, and sporulation behaviors. A high resolution mass spectrometry-based proteomics analysis defined the extracellular proteases secreted by F. graminearum. A meta-classification based on sequence characters and transcriptional/translational activity in planta and in vitro provides a platform to develop control strategies that target Fgr peptidases.

  4. How Bacterial Pathogens Eat Host Lipids: Implications for the Development of Fatty Acid Synthesis Therapeutics*

    PubMed Central

    Yao, Jiangwei; Rock, Charles O.

    2015-01-01

    Bacterial type II fatty acid synthesis (FASII) is a target for the development of novel therapeutics. Bacteria incorporate extracellular fatty acids into membrane lipids, raising the question of whether pathogens use host fatty acids to bypass FASII and defeat FASII therapeutics. Some pathogens suppress FASII when exogenous fatty acids are present to bypass FASII therapeutics. FASII inhibition cannot be bypassed in many bacteria because essential fatty acids cannot be obtained from the host. FASII antibiotics may not be effective against all bacteria, but a broad spectrum of Gram-negative and -positive pathogens can be effectively treated with FASII inhibitors. PMID:25648887

  5. Incorporation of bacterial extracellular polysaccharide by black fly larvae (Simuliidae)

    USGS Publications Warehouse

    Couch, C.A.; Meyer, J.L.; Hall, R.O.

    1996-01-01

    Black fly larvae (Simulium) assimilated, with high efficiency (80-90%), bacterial extracellular polysaccharide (EPS) extracted from laboratory cultures of a pseudomonad isolated from the Ogeechee River. Incorporation was traced using 13C-labelled EPS offered to larvae as a coating on a mixture of 1-??m latex beads and kaolin particles. These EPS-coated particles were used to simulate natural particles, both living and dead. Solubility, protein, and nitrogen content of the EPS suggested it was a slime rather than a capsular polysaccharide. Glycosyl composition of the EPS was glucose and galactose in ?? and ?? linkages, with pyruvate, succinate, and possibly malonate constituent groups. To evaluate the incorporation of C derived from protein associated with the EPS matrix, feeding experiments were conducted using EPS with and without proteins extracted. Black fly larvae incorporated 7.2 ??g EPS C larva-1 d-1 from EPS that did not have proteins extracted, and 19.5 ??g EPS C larva-1 d-1 from EPS with proteins extracted. Carbon in protein that is typically associated with EPS was not solely or selectively incorporated. EPS incorporation rates are similar to rates of cellular bacterial carbon incorporation previously estimated for Ogeechee River black fly larvae. If EPS is generally available as a food resource, the importance of bacteria in detrital food webs may be underestimated by studies that examine only the consumption of bacterial cells.

  6. Manipulation of host membrane machinery by bacterial pathogens

    PubMed Central

    Cossart, Pascale; Roy, Craig R.

    2010-01-01

    Subversion of host membrane machinery is important for the uptake, survival, and replication of bacterial pathogens. Understanding how pathogens manipulate host membrane transport pathways provides mechanistic insight into how infection occurs and is also revealing new information on biochemical processes involved in the functioning of eukaryotic cells. In this review we discuss several of the canonical host pathways targeted by bacterial pathogens and emerging areas of investigation in this exciting field. PMID:20542678

  7. Extracellular Superoxide Dismutase Inhibits Innate Immune Responses and Clearance of an Intracellular Bacterial Infection

    PubMed Central

    Break, Timothy J.; Jun, Sujung; Indramohan, Mohanalaxmi; Carr, Karen D.; Sieve, Amy N.; Dory, Ladislav; Berg, Rance E.

    2012-01-01

    Reactive oxygen and nitrogen species (ROS/RNS) play important roles during immune responses to bacterial pathogens. Extracellular superoxide dismutase (ecSOD) regulates extracellular concentrations of ROS/RNS and contributes to tissue protection during inflammatory insults. The participation of ecSOD in immune responses seems therefore intuitive, yet is poorly understood. In the present study, we utilized mice with varying levels of ecSOD activity to investigate the involvement of this enzyme in immune responses against Listeria monocytogenes. Surprisingly, our data demonstrate that, despite enhanced neutrophil recruitment to the liver, ecSOD activity negatively impacted host survival and bacterial clearance. Increased ecSOD activity was accompanied by decreased co-localization of neutrophils with bacteria, as well as increased neutrophil apoptosis, which reduced overall and neutrophil-specific TNF-α production. Liver leukocytes from mice lacking ecSOD produced equivalent nitric oxide (NO·) when compared to mice expressing ecSOD. However, during infection, there were higher levels of peroxynitrite (NO3·−) in livers from mice lacking ecSOD compared to mice expressing ecSOD. Neutrophil depletion studies revealed that high levels of ecSOD activity resulted in neutrophils with limited protective capacity, whereas neutrophils from mice lacking ecSOD provided superior protection compared to neutrophils from wild-type mice. Taken together, our data demonstrate that ecSOD activity reduces innate immune responses during bacterial infection and provides a potential target for therapeutic intervention. PMID:22393157

  8. Extracellular bacterial mineralization within the context of geomicrobiology.

    PubMed

    Ben Omar, N; Arias, J M; González-Muñoz, M T

    1997-06-01

    In the biosphere, bacteria can function as geochemical agents, promoting the dispersion, fractionation and/or concentration of matter. These processes, which are being more and more valued from the point of view of various scientific disciplines, have given rise to the field of geomicrobiology. At the same time, microbial processes resulting in the concentration of matter and thus inducing the formation of minerals, constitute an area of research of growing interest known as biomineralization. In this review a succinct summary of various aspects of both disciplines has been offered together with a more detailed review of those aspects related to extracellular bacterial mineralization. The significance of the role played by the metabolism of bacteria is discussed along with the results of recent research on the role of dead bacteria and bacterial remains that act as heterogeneous nuclei of crystallization. The role played by the membranes of bacteria has also been considered to be highly relevant, and a discussion concerning their possible value as models for both the study of more complex biomineralization processes as well as application in the field of biomimetic materials is put forward.

  9. Diagnostics and Resistance Profiling of Bacterial Pathogens.

    PubMed

    Hornischer, Klaus; Häußler, Susanne

    Worldwide infectious disease is one of the leading causes of death. Despite improvements in technology and healthcare services, morbidity and mortality due to infections have remained unchanged over the past few decades. The high and increasing rate of antibiotic resistance is further aggravating the situation. Growing resistance hampers the use of conventional antibiotics, and substantial higher mortality rates are reported in patients given ineffective empiric therapy mainly due to resistance to the agents used. These infections cause suffering, incapacity, and death and impose an enormous financial burden on both healthcare systems and on society in general. The accelerating development of multidrug resistance is one of the greatest diagnostic and therapeutic challenges to modern medicine. The lack of new antibiotic options underscores the need for optimization of current diagnostics, therapies, and prevention of the spread of multidrug-resistant organisms. The so-called -omics technologies (genomics, transcriptomics, proteomics, and metabolomics) have yielded large-scale datasets that advanced the search for biomarkers of infectious diseases in the last decade. One can imagine that in the future the implementation of biomarker-driven molecular test systems will transform diagnostics of infectious diseases and will significantly accelerate the identification of the bacterial pathogens at the infected host site. Furthermore, molecular tests based on the identification of markers of antibiotic resistance will dramatically change resistance profiling. The replacement of culturing methods by molecular test systems for early diagnosis will provide the basis not only for a prompt and targeted therapy, but also for a much more effective stewardship of antibiotic agents and a reduction of the spread of multidrug resistance as well as the appearance of new antibiotic resistances.

  10. Characterization and isolation of an extracellular serine protease from the tomato pathogen Colletotrichum coccodes, and it's role in pathogenicity

    USGS Publications Warehouse

    Redman, R.S.; Rodriguez, R.J.

    2002-01-01

    Extracellular enzymes play an important role in the pathogenicity and virulence of phytopathogenic fungi. Several isolates of Colletotrichum coccodes, causal agent of anthracnose on tomato, were screened to determine the relationship between protease activity and virulence. A direct relationship was observed between extracellular protease activity and the induction of disease symptoms of fruit and mortality in plants. Isolate Cc155 exhibited the highest protease activity after five days of growth in protease induction medium and produced an extracellular serine protease (sp78) that was 78 kDa, auto-degradative, glucose repressible, and non-glycosylated. To determine the role of sp78 in pathogenicity, a uv-induced extracellular protease deficient mutant (np155) was generated from the wildtype isolate Cc155. Np155 maintained growth rates comparable to Cc155 and produced wildtype levels of extracellular cellulase but did not produce extracellular protease. Unlike Cc155, np155 caused no disease symptoms on tomato fruit and 0% mortality on tomato seedlings. These results suggest that extracellular protease activity is required for pathogenicity and virulence of C. coccodes, and that the elimination of protease activity transforms a virulent pathogen to a non-pathogenic endophyte.

  11. Characterization and isolation of an extracellular serine protease from the tomato pathogen Colletotrichum coccodes, and it's role in pathogenicity

    USGS Publications Warehouse

    Redman, Regina S.; Rodriguez, Rusty J.

    2002-01-01

    Extracellular enzymes play an important role in the pathogenicity and virulence of phytopathogenic fungi. Several isolates of Colletotrichum coccodes causal agent of anthracnose on tomato, were screened to determine the relationship between protease activity and virulence. A direct relationship was observed between extracellular protease activity and the induction of disease symptoms of fruit and mortality in plants. Isolate Cc155 exhibited the highest protease activity after five days of growth in protease induction medium and produced an extracellular serine protease (sp78) that was 78 kDa, auto-degradative, glucose repressible, and non-glycosylated. To determine the role of sp78 in pathogenicity, a UV-induced extracellular protease deficient mutant (np155) was generated from the wildtype isolate Cc155. Np155 maintained growth rates comparable to Cc155 and produced wildtype levels of extracellular cellulase but did not produce extracellular protease. Unlike Cc155, np155 caused no disease symptoms on tomato fruit and 0% mortality on tomato seedlings. These results suggest that extracellular protease activity is required for pathogenicity and virulence of C. coccodes and that the elimination of protease activity transforms a virulent pathogen to a non-pathogenic endophyte.

  12. Evolution of Bacterial Pathogens within the Human Host

    PubMed Central

    Bliven, Kimberly A.; Maurelli, Anthony T.

    2015-01-01

    Selective pressures within the human host, including interactions with innate and adaptive immune responses, exposure to medical interventions such as antibiotics, and competition with commensal microbiota all facilitate the evolution of bacterial pathogens. In this chapter, we present examples of pathogen strategies which emerged as a result of selective pressures within the human host niche, and discuss the resulting co-evolutionary ‘arms race’ between these organisms. In bacterial pathogens, many of the genes responsible for these strategies are encoded on mobile pathogenicity islands (PAIs) or plasmids, underscoring the importance of horizontal gene transfer (HGT) in the emergence of virulent microbial species. PMID:26999399

  13. Molecular population genetic analysis of emerged bacterial pathogens: selected insights.

    PubMed Central

    Musser, J. M.

    1996-01-01

    Research in bacterial population genetics has increased in the last 10 years. Population genetic theory and tools and related strategies have been used to investigate bacterial pathogens that have contributed to recent episodes of temporal variation in disease frequency and severity. A common theme demonstrated by these analyses is that distinct bacterial clones are responsible for disease outbreaks and increases in infection frequency. Many of these clones are characterized by unique combinations of virulence genes or alleles of virulence genes. Because substantial interclonal variance exists in relative virulence, molecular population genetic studies have led to the concept that the unit of bacterial pathogenicity is the clone or cell line. Continued new insights into host parasite interactions at the molecular level will be achieved by combining clonal analysis of bacterial pathogens with large-scale comparative sequencing of virulence genes. PMID:8903193

  14. Definition of the extracellular proteome of pathogenic-phase Histoplasma capsulatum.

    PubMed

    Holbrook, Eric D; Edwards, Jessica A; Youseff, Brian H; Rappleye, Chad A

    2011-04-01

    The dimorphic fungal pathogen Histoplasma capsulatum causes respiratory and systemic disease. Within the mammalian host, pathogenic Histoplasma yeast infect, replicate within, and ultimately kill host phagocytes. Surprisingly, few factors have been identified that contribute to Histoplasma virulence. To address this deficiency, we have defined the constituents of the extracellular proteome using LC-MS/MS analysis of the proteins in pathogenic-phase culture filtrates of Histoplasma. In addition to secreted Cbp1, the extracellular proteome of pathogenic Histoplasma yeast consists of 33 deduced proteins. The proteins include glycanases, extracellular enzymes related to oxidative stress defense, dehydrogenase enzymes, chaperone-like factors, and five novel culture filtrate proteins (Cfp's). For independent verification of proteomics-derived identities, we employed RNA interference (RNAi)-based depletion of candidate factors and showed loss of specific proteins from the cell-free culture filtrate. Quantitative RT-PCR revealed the expression of 10 of the extracellular factors was particularly enriched in pathogenic yeast cells as compared to nonpathogenic Histoplasma mycelia, suggesting that these proteins are linked to Histoplasma pathogenesis. In addition, Histoplasma yeast express these factors within macrophages and during infection of murine lungs. As extracellular proteins are positioned at the interface between host and pathogen, the definition of the pathogenic-phase extracellular proteome provides a foundation for the molecular dissection of how Histoplasma alters the host-pathogen interaction to its advantage.

  15. Technologies for Proteome-Wide Discovery of Extracellular Host-Pathogen Interactions

    PubMed Central

    2017-01-01

    Pathogens have evolved unique mechanisms to breach the cell surface barrier and manipulate the host immune response to establish a productive infection. Proteins exposed to the extracellular environment, both cell surface-expressed receptors and secreted proteins, are essential targets for initial invasion and play key roles in pathogen recognition and subsequent immunoregulatory processes. The identification of the host and pathogen extracellular molecules and their interaction networks is fundamental to understanding tissue tropism and pathogenesis and to inform the development of therapeutic strategies. Nevertheless, the characterization of the proteins that function in the host-pathogen interface has been challenging, largely due to the technical challenges associated with detection of extracellular protein interactions. This review discusses available technologies for the high throughput study of extracellular protein interactions between pathogens and their hosts, with a focus on mammalian viruses and bacteria. Emerging work illustrates a rich landscape for extracellular host-pathogen interaction and points towards the evolution of multifunctional pathogen-encoded proteins. Further development and application of technologies for genome-wide identification of extracellular protein interactions will be important in deciphering functional host-pathogen interaction networks, laying the foundation for development of novel therapeutics. PMID:28321417

  16. The influence of the accessory genome on bacterial pathogen evolution

    PubMed Central

    Vinatzer, Boris; Arnold, Dawn L; Dorus, Steve; Murillo, Jesús

    2011-01-01

    Bacterial pathogens exhibit significant variation in their genomic content of virulence factors. This reflects the abundance of strategies pathogens evolved to infect host organisms by suppressing host immunity. Molecular arms-races have been a strong driving force for the evolution of pathogenicity, with pathogens often encoding overlapping or redundant functions, such as type III protein secretion effectors and hosts encoding ever more sophisticated immune systems. The pathogens' frequent exposure to other microbes, either in their host or in the environment, provides opportunities for the acquisition or interchange of mobile genetic elements. These DNA elements accessorize the core genome and can play major roles in shaping genome structure and altering the complement of virulence factors. Here, we review the different mobile genetic elements focusing on the more recent discoveries and highlighting their role in shaping bacterial pathogen evolution. PMID:22016845

  17. Spatiotemporal Dynamics of Complement C5a Production within Bacterial Extracellular Polymeric Substance

    PubMed Central

    Conrad, Erin C.; Hsu, Yueh-Ya; Bortz, David M.; Younger, John G.

    2013-01-01

    Opsonization and anaphylatoxin production are early events in innate response to bacterial pathogens. Opsonization alone is frequently not lethal and production of anaphylatoxins, especially C5a, allows for recruitment of cellular defenses. Complement biochemistry is extensively studied and computational models have been previously reported. However, a critical feature of complement mediated attack is its spatial dependence: diffusion of mediators into and away from a bacterium is central to understanding C5a generation. Spatial dependence is especially important in biofilms, where diffusion limitation is crucial to bacterial counterdefense. Here we develop a model of opsonization and C5a production in the presence of a common blood borne pathogen, Staphylococcus epidermidis. Our results indicate that when complement attacks a single cell, diffusion into the extracellular polymeric substance (EPS) is complete within 10 msec and that production of C5a peaks over the next 15 minutes. When longer diffusion lengths (as in an EPS-rich biofilm) are incorporated, diffusion limitation appears such that the intensity and duration of C5a production is increased. However, the amount of C5a produced under several likely clinical scenarios where single cells or sparse biofilms are present is below the kD of the C5a receptor suggesting that complement activation by a single bacterium may be difficult to detect when diffusion is taken into account. PMID:23328643

  18. Bacterial metabolism shapes the host:pathogen interface

    PubMed Central

    Passalacqua, Karla D.; Charbonneau, Marie-Eve; O'Riordan, Mary X.D.

    2016-01-01

    Summary Bacterial pathogens have evolved to exploit humans as a rich source of nutrients to support survival and replication. The pathways of bacterial metabolism that permit successful colonization are surprisingly varied and highlight remarkable metabolic flexibility. The constraints and immune pressures of distinct niches within the human body set the stage for understanding the mechanisms by which bacteria acquire critical nutrients. Here we discuss how different bacterial pathogens carry out carbon and energy metabolism in the host, and how they obtain or use key nutrients for replication and immune evasion. PMID:27337445

  19. The bacterial microbiome of Dermacentor andersoni ticks influences pathogen susceptibility

    PubMed Central

    Gall, Cory A; Reif, Kathryn E; Scoles, Glen A; Mason, Kathleen L; Mousel, Michelle; Noh, Susan M; Brayton, Kelly A

    2016-01-01

    Ticks are of medical importance owing to their ability to transmit pathogens to humans and animals. The Rocky Mountain wood tick, Dermacentor andersoni, is a vector of a number of pathogens, including Anaplasma marginale, which is the most widespread tick-borne pathogen of livestock. Although ticks host pathogenic bacteria, they also harbor bacterial endosymbionts that have a role in tick physiology, survival, as well as pathogen acquisition and transmission. The goal of this study was to characterize the bacterial microbiome and examine the impact of microbiome disruption on pathogen susceptibility. The bacterial microbiome of two populations of D. andersoni with historically different susceptibilities to A. marginale was characterized. In this study, the microbiome was disrupted and then ticks were exposed to A. marginale or Francisella novicida to determine whether the microbiome correlated with pathogen susceptibility. Our study showed that an increase in proportion and quantity of Rickettsia bellii in the microbiome was negatively correlated to A. marginale levels in ticks. Furthermore, a decrease in Francisella endosymbionts was associated with lower F. novicida infection levels, demonstrating a positive pathogen–endosymbiont relationship. We demonstrate that endosymbionts and pathogens have varying interactions, and suggest that microbiome manipulation may provide a possible method for biocontrol by decreasing pathogen susceptibility of ticks. PMID:26882265

  20. The diversity of bacterial pathogenicity mechanisms.

    PubMed

    Rosenberg, Eugene

    2005-01-01

    A report on the international conference 'Molecular basis of bacterial pathogenesis', sponsored by the Federation of European Microbiological Societies (FEMS) and the Israel Center for the Study of Emerging Diseases, Ein Gedi, Israel, 23-27 January 2005.

  1. The diversity of bacterial pathogenicity mechanisms

    PubMed Central

    Rosenberg, Eugene

    2005-01-01

    A report on the international conference 'Molecular basis of bacterial pathogenesis', sponsored by the Federation of European Microbiological Societies (FEMS) and the Israel Center for the Study of Emerging Diseases, Ein Gedi, Israel, 23-27 January 2005. PMID:15892881

  2. Genomic and Transcriptomic Analyses of Foodborne Bacterial Pathogens

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Dudley, Edward G.; Wade, Joseph T.

    DNA microarrays (often interchangeably called DNA chips or DNA arrays) are among the most popular analytical tools for high-throughput comparative genomic and transcriptomic analyses of foodborne bacterial pathogens. A typical DNA microarray contains hundreds to millions of small DNA probes that are chemically attached (or "printed") onto the surface of a microscopic glass slide. Depending on the specific "printing" and probe synthesis technologies for different microarray platforms, such DNA probes can be PCR amplicons or in situ synthesized short oligonucleotides. DNA microarray technologies have revolutionized the way that we investigate the biology of foodborne bacterial pathogens. The major advantage of these technologies is that DNA microarrays allow comparison of subtle genomic or transcriptomic variations between two bacterial samples, such as genomic variations between two different bacterial strains or transcriptomic alterations of same bacterial strain under two different treatments. Some applications of comparative genomic hybridization microarrays and global gene expression microarrays have been covered in previous chapters of this book.

  3. [Oral bacterial flora and its pathogenic potential].

    PubMed

    Madinier, I

    1991-03-01

    The oral flora is a complex body formed by at least a hundred bacterial species which can be more or less regular residents in the oral cavity. Thanks to a developing taxonomy related to progress made in bacterial identification, these oral species can be separated into five groups based Gram staining and morphology: the Gram positive cocci group (Streptococcus, Staphylococcus and related geni), the Gram negative cocci group (Neisseria, Veillonella and related geni), the Gram positive bacilli group (Corynebacterium, Actinomyces, Lactobacillus, Methanobrevibacter and related geni), the Gram negative bacilli group (Haemophilus, Campylobacter, Bacteroides and related geni) and finally the spirochete group (Treponema).

  4. Looking in ticks for human bacterial pathogens.

    PubMed

    Mediannikov, O; Fenollar, F

    2014-12-01

    Ticks are considered to be second worldwide to mosquitoes as vectors of human diseases and the most important vectors of disease-causing pathogens in domestic and wild animals. A number of emerging tick-borne pathogens are already discovered; however, the proportion of undiagnosed infectious diseases, especially in tropical regions, may suggest that there are still more pathogens associated with ticks. Moreover, the identification of bacteria associated with ticks may provide new tool for the control of ticks and tick-borne diseases. Described here molecular methods of screening of ticks, extensive use of modern culturomics approach, newly developed artificial media and different cell line cultures may significantly improve our knowledge about the ticks as the agents of human and animal pathology.

  5. Pathogen espionage: multiple bacterial adrenergic sensors eavesdrop on host communication systems.

    PubMed

    Karavolos, Michail H; Winzer, Klaus; Williams, Paul; Khan, C M Anjam

    2013-02-01

    The interactions between bacterial pathogens and their eukaryotic hosts are vital in determining the outcome of infections. Bacterial pathogens employ molecular sensors to detect and facilitate adaptation to changes in their niche. The sensing of these extracellular signals enables the pathogen to navigate within mammalian hosts. Intercellular bacterial communication is facilitated by the production and sensing of autoinducer (AI) molecules via quorum sensing. More recently, AI-3 and the host neuroendocrine (NE) hormones adrenaline and noradrenaline were reported to display cross-talk for the activation of the same signalling pathways. Remarkably, there is increasing evidence to suggest that enteric bacteria sense and respond to the host NE stress hormones adrenaline and noradrenaline to modulate virulence. These responses can be inhibited by α and β-adrenergic receptor antagonists implying a bacterial receptor-based sensing and signalling cascade. In Escherichia coli O157:H7 and Salmonella, QseC has been proposed as the adrenergic receptor. Strikingly, there is an increasing body of evidence that not all the bacterial adrenergic responses require signalling through QseC. Here we provide additional hypotheses to reconcile these observations implicating the existence of alternative adrenergic receptors including BasS, QseE and CpxA and their associated signalling cascades with major roles in interkingdom communication.

  6. A chronological study of the bacterial pathogen changes in acute neonatal bacterial conjunctivitis in southern China.

    PubMed

    Tang, Song; Li, Ming; Chen, Hongbo; Ping, Guo; Zhang, Chun; Wang, Shusheng

    2017-09-26

    The aim of the project is to retrospectively study the changes in bacterial pathogens in acute neonatal bacterial conjunctivitis from 2002 to 2016 in Southern China. The results may provide the guidance for drug choice for acute neonatal bacterial conjunctivitis. Secretion specimens for bacterial culture were taken from 485 cases with clinically diagnosed acute bacterial neonatal conjunctivitis. Bacterial pathogens were detected by Gram staining and subsequent bacterial culture. From the analysis of the bacterial pathogens in 485 cases of acute neonatal conjunctivitis patients from 2002 to 2016 in Southern China, there is an overall trend of decreasing detection of Gram-positive bacteria and increasing detection of Gram-negative bacteria from the conjunctival sac secretions. Gram-positive bacteria in the bacteria-positive samples dropped year by year from 82.6% in 2002 to 72.4% in 2016. Accordingly, the ratio of Gram-negative bacteria increased from 17.4% in 2002 to 27.6% in 2016. Of note, despite the overall trend, there was a significant increase in detection of Gram-positive bacteria and decrease in detection of Gram-negative bacteria from 2011 to 2012. Among the Gram-positive bacteria, there is a trend of increasing percentage of the opportunistic pathogens (an ~60% increase in Staphylococcus epidermidis and Staphylococcus saprophytic) and decreasing percentage of Staphylococcus aureus (~30% decrease) and hemolytic streptococcus (~20% decrease) in the last 15 years. The main Gram-negative bacterium is Neisseria gonorrhoeae. Overall, there is a change in the pattern of bacterial species in acute neonatal bacterial conjunctivitis in Southern China in the last 15 years. Our study provides a trend analysis of the bacterial pathogens in the conjunctival sac secretions of the acute neonatal bacterial conjunctivitis patients in Southern China in recent years. This data could provide useful information regarding the treatment options for neonatal bacterial

  7. Cytosolic Access of Intracellular Bacterial Pathogens: The Shigella Paradigm.

    PubMed

    Mellouk, Nora; Enninga, Jost

    2016-01-01

    Shigella is a Gram-negative bacterial pathogen, which causes bacillary dysentery in humans. A crucial step of Shigella infection is its invasion of epithelial cells. Using a type III secretion system, Shigella injects several bacterial effectors ultimately leading to bacterial internalization within a vacuole. Then, Shigella escapes rapidly from the vacuole, it replicates within the cytosol and spreads from cell-to-cell. The molecular mechanism of vacuolar rupture used by Shigella has been studied in some detail during the recent years and new paradigms are emerging about the underlying molecular events. For decades, bacterial effector proteins were portrayed as main actors inducing vacuolar rupture. This includes the effector/translocators IpaB and IpaC. More recently, this has been challenged and an implication of the host cell in the process of vacuolar rupture has been put forward. This includes the bacterial subversion of host trafficking regulators, such as the Rab GTPase Rab11. The involvement of the host in determining bacterial vacuolar integrity has also been found for other bacterial pathogens, particularly for Salmonella. Here, we will discuss our current view of host factor and pathogen effector implications during Shigella vacuolar rupture and the steps leading to it.

  8. Cytosolic Access of Intracellular Bacterial Pathogens: The Shigella Paradigm

    PubMed Central

    Mellouk, Nora; Enninga, Jost

    2016-01-01

    Shigella is a Gram-negative bacterial pathogen, which causes bacillary dysentery in humans. A crucial step of Shigella infection is its invasion of epithelial cells. Using a type III secretion system, Shigella injects several bacterial effectors ultimately leading to bacterial internalization within a vacuole. Then, Shigella escapes rapidly from the vacuole, it replicates within the cytosol and spreads from cell-to-cell. The molecular mechanism of vacuolar rupture used by Shigella has been studied in some detail during the recent years and new paradigms are emerging about the underlying molecular events. For decades, bacterial effector proteins were portrayed as main actors inducing vacuolar rupture. This includes the effector/translocators IpaB and IpaC. More recently, this has been challenged and an implication of the host cell in the process of vacuolar rupture has been put forward. This includes the bacterial subversion of host trafficking regulators, such as the Rab GTPase Rab11. The involvement of the host in determining bacterial vacuolar integrity has also been found for other bacterial pathogens, particularly for Salmonella. Here, we will discuss our current view of host factor and pathogen effector implications during Shigella vacuolar rupture and the steps leading to it. PMID:27092296

  9. Intracellular activity of azithromycin against bacterial enteric pathogens.

    PubMed Central

    Rakita, R M; Jacques-Palaz, K; Murray, B E

    1994-01-01

    Azithromycin, a new azalide antibiotic, is active in vitro against a variety of enteric bacterial pathogens. Since it is concentrated inside human neutrophils and other cells, it might be particularly useful in the treatment of infections caused by enteropathogens that invade host tissues. The intracellular activity of azithromycin against several enteric pathogens that had been phagocytosed by neutrophils was determined. Azithromycin was effective in reducing the intracellular viabilities of almost all strains tested, including representative strains of Salmonella, Shigella, and enteroinvasive, enteropathogenic, enterotoxigenic, and enterohemorrhagic Escherichia coli. Erythromycin was also effective in this model system, although azithromycin was generally more effective than erythromycin against strains of invasive enteric pathogens. Cefotaxime reduced intracellular bacterial viability to a lesser extent than either azithromycin or erythromycin. The presence of neutrophils did not significantly affect the activity of azithromycin in this system. Azithromycin may be a useful agent for the treatment of bacterial diarrhea, and clinical trials should be considered. PMID:7810998

  10. Autophagic clearance of bacterial pathogens: molecular recognition of intracellular microorganisms.

    PubMed

    Pareja, Maria Eugenia Mansilla; Colombo, Maria I

    2013-01-01

    Autophagy is involved in several physiological and pathological processes. One of the key roles of the autophagic pathway is to participate in the first line of defense against the invasion of pathogens, as part of the innate immune response. Targeting of intracellular bacteria by the autophagic machinery, either in the cytoplasm or within vacuolar compartments, helps to control bacterial proliferation in the host cell, controlling also the spreading of the infection. In this review we will describe the means used by diverse bacterial pathogens to survive intracellularly and how they are recognized by the autophagic molecular machinery, as well as the mechanisms used to avoid autophagic clearance.

  11. Autophagic clearance of bacterial pathogens: molecular recognition of intracellular microorganisms

    PubMed Central

    Mansilla Pareja, Maria Eugenia; Colombo, Maria I.

    2013-01-01

    Autophagy is involved in several physiological and pathological processes. One of the key roles of the autophagic pathway is to participate in the first line of defense against the invasion of pathogens, as part of the innate immune response. Targeting of intracellular bacteria by the autophagic machinery, either in the cytoplasm or within vacuolar compartments, helps to control bacterial proliferation in the host cell, controlling also the spreading of the infection. In this review we will describe the means used by diverse bacterial pathogens to survive intracellularly and how they are recognized by the autophagic molecular machinery, as well as the mechanisms used to avoid autophagic clearance. PMID:24137567

  12. Metabolic host responses to infection by intracellular bacterial pathogens

    PubMed Central

    Eisenreich, Wolfgang; Heesemann, Jürgen; Rudel, Thomas; Goebel, Werner

    2013-01-01

    The interaction of bacterial pathogens with mammalian hosts leads to a variety of physiological responses of the interacting partners aimed at an adaptation to the new situation. These responses include multiple metabolic changes in the affected host cells which are most obvious when the pathogen replicates within host cells as in case of intracellular bacterial pathogens. While the pathogen tries to deprive nutrients from the host cell, the host cell in return takes various metabolic countermeasures against the nutrient theft. During this conflicting interaction, the pathogen triggers metabolic host cell responses by means of common cell envelope components and specific virulence-associated factors. These host reactions generally promote replication of the pathogen. There is growing evidence that pathogen-specific factors may interfere in different ways with the complex regulatory network that controls the carbon and nitrogen metabolism of mammalian cells. The host cell defense answers include general metabolic reactions, like the generation of oxygen- and/or nitrogen-reactive species, and more specific measures aimed to prevent access to essential nutrients for the respective pathogen. Accurate results on metabolic host cell responses are often hampered by the use of cancer cell lines that already exhibit various de-regulated reactions in the primary carbon metabolism. Hence, there is an urgent need for cellular models that more closely reflect the in vivo infection conditions. The exact knowledge of the metabolic host cell responses may provide new interesting concepts for antibacterial therapies. PMID:23847769

  13. Interspecies Communication between Pathogens and Immune Cells via Bacterial Membrane Vesicles

    PubMed Central

    Jurkoshek, Katerina S.; Wang, Ying; Athman, Jaffre J.; Barton, Marian R.; Wearsch, Pamela A.

    2016-01-01

    The production of extracellular vesicles is a universal mechanism for intercellular communication that is conserved across kingdoms. Prokaryotes secrete 50–250 nm membrane vesicles (MVs) in a manner that is regulated by environmental stress and is thought to promote survival. Since many types of host-derived stress are encountered during infection, this implies an important role for MV secretion in bacterial pathogenesis. Accordingly, MVs produced by gram-positive and gram-negative pathogens contain toxins, virulence factors, and other molecules that promote survival in the host. However, recent studies have also shown that bacterial MVs are enriched for molecules that stimulate innate and adaptive immune responses. As an example, MVs may serve multiple, important roles in regulating the host response to Mycobacterium tuberculosis (Mtb), an intracellular pathogen that infects lung macrophages and resides within modified phagosomes. Previously, we demonstrated that Mtb secretes MVs during infection that may modulate infected and uninfected immune cells. Our present data demonstrates that Mtb MVs inhibit the functions of macrophages and T cells, but promote Major Histocompatibility Complex (MHC) class II antigen presentation by dendritic cells. We conclude that bacterial MVs serve dual and opposing roles in the activation of and defense against host immune responses to Mtb and other bacterial pathogens. We also propose that MV secretion is a central mechanism for interspecies communication between bacteria and host cells during infection. PMID:27891500

  14. Kynetic resazurin assay (KRA) for bacterial quantification of foodborne pathogens

    NASA Astrophysics Data System (ADS)

    Arenas, Yaxal; Mandel, Arkady; Lilge, Lothar

    2012-03-01

    Fast detection of bacterial concentrations is important for the food industry and for healthcare. Early detection of infections and appropriate treatment is essential since, the delay of treatments for bacterial infections tends to be associated with higher mortality rates. In the food industry and in healthcare, standard procedures require the count of colony-forming units in order to quantify bacterial concentrations, however, this method is time consuming and reports require three days to be completed. An alternative is metabolic-colorimetric assays which provide time efficient in vitro bacterial concentrations. A colorimetric assay based on Resazurin was developed as a time kinetic assay (KRA) suitable for bacterial concentration measurements. An optimization was performed by finding excitation and emission wavelengths for fluorescent acquisition. A comparison of two non-related bacteria, foodborne pathogens Escherichia coli and Listeria monocytogenes, was performed in 96 well plates. A metabolic and clonogenic dependence was established for fluorescent kinetic signals.

  15. Bithionol blocks pathogenicity of bacterial toxins, ricin, and Zika virus

    USDA-ARS?s Scientific Manuscript database

    Disease pathways form overlapping networks, and hub proteins represent attractive targets for broad-spectrum drugs. Using bacterial toxins as a proof of concept, we describe a new approach of discovering broad-spectrum therapies capable of inhibiting host proteins that mediate multiple pathogenic pa...

  16. Menaquinone Analogs Inhibit Growth of Bacterial Pathogens

    PubMed Central

    Merriman, Joseph A.; Salgado-Pabón, Wilmara; Mueller, Elizabeth A.; Spaulding, Adam R.; Vu, Bao G.; Chuang-Smith, Olivia N.; Kohler, Petra L.; Kirby, John R.

    2013-01-01

    Gram-positive bacteria cause serious human illnesses through combinations of cell surface and secreted virulence factors. We initiated studies with four of these organisms to develop novel topical antibacterial agents that interfere with growth and exotoxin production, focusing on menaquinone analogs. Menadione, 1,4-naphthoquinone, and coenzymes Q1 to Q3 but not menaquinone, phylloquinone, or coenzyme Q10 inhibited the growth and to a greater extent exotoxin production of Staphylococcus aureus, Bacillus anthracis, Streptococcus pyogenes, and Streptococcus agalactiae at concentrations of 10 to 200 μg/ml. Coenzyme Q1 reduced the ability of S. aureus to cause toxic shock syndrome in a rabbit model, inhibited the growth of four Gram-negative bacteria, and synergized with another antimicrobial agent, glycerol monolaurate, to inhibit S. aureus growth. The staphylococcal two-component system SrrA/B was shown to be an antibacterial target of coenzyme Q1. We hypothesize that menaquinone analogs both induce toxic reactive oxygen species and affect bacterial plasma membranes and biosynthetic machinery to interfere with two-component systems, respiration, and macromolecular synthesis. These compounds represent a novel class of potential topical therapeutic agents. PMID:23959313

  17. Menaquinone analogs inhibit growth of bacterial pathogens.

    PubMed

    Schlievert, Patrick M; Merriman, Joseph A; Salgado-Pabón, Wilmara; Mueller, Elizabeth A; Spaulding, Adam R; Vu, Bao G; Chuang-Smith, Olivia N; Kohler, Petra L; Kirby, John R

    2013-11-01

    Gram-positive bacteria cause serious human illnesses through combinations of cell surface and secreted virulence factors. We initiated studies with four of these organisms to develop novel topical antibacterial agents that interfere with growth and exotoxin production, focusing on menaquinone analogs. Menadione, 1,4-naphthoquinone, and coenzymes Q1 to Q3 but not menaquinone, phylloquinone, or coenzyme Q10 inhibited the growth and to a greater extent exotoxin production of Staphylococcus aureus, Bacillus anthracis, Streptococcus pyogenes, and Streptococcus agalactiae at concentrations of 10 to 200 μg/ml. Coenzyme Q1 reduced the ability of S. aureus to cause toxic shock syndrome in a rabbit model, inhibited the growth of four Gram-negative bacteria, and synergized with another antimicrobial agent, glycerol monolaurate, to inhibit S. aureus growth. The staphylococcal two-component system SrrA/B was shown to be an antibacterial target of coenzyme Q1. We hypothesize that menaquinone analogs both induce toxic reactive oxygen species and affect bacterial plasma membranes and biosynthetic machinery to interfere with two-component systems, respiration, and macromolecular synthesis. These compounds represent a novel class of potential topical therapeutic agents.

  18. Modulation of Host miRNAs by Intracellular Bacterial Pathogens

    PubMed Central

    Das, Kishore; Garnica, Omar; Dhandayuthapani, Subramanian

    2016-01-01

    MicroRNAs (miRNAs) are short non-coding RNAs that regulate the expression of protein coding genes of viruses and eukaryotes at the post-transcriptional level. The eukaryotic genes regulated by miRNAs include those whose products are critical for biological processes such as cell proliferation, metabolic pathways, immune response, and development. It is now increasingly recognized that modulation of miRNAs associated with biological processes is one of the strategies adopted by bacterial pathogens to survive inside host cells. In this review, we present an overview of the recent findings on alterations of miRNAs in the host cells by facultative intracellular bacterial pathogens. In addition, we discuss how the altered miRNAs help in the survival of these pathogens in the intracellular environment. PMID:27536558

  19. Unraveling Plant Responses to Bacterial Pathogens through Proteomics

    PubMed Central

    Zimaro, Tamara; Gottig, Natalia; Garavaglia, Betiana S.; Gehring, Chris; Ottado, Jorgelina

    2011-01-01

    Plant pathogenic bacteria cause diseases in important crops and seriously and negatively impact agricultural production. Therefore, an understanding of the mechanisms by which plants resist bacterial infection at the stage of the basal immune response or mount a successful specific R-dependent defense response is crucial since a better understanding of the biochemical and cellular mechanisms underlying these interactions will enable molecular and transgenic approaches to crops with increased biotic resistance. In recent years, proteomics has been used to gain in-depth understanding of many aspects of the host defense against pathogens and has allowed monitoring differences in abundance of proteins as well as posttranscriptional and posttranslational processes, protein activation/inactivation, and turnover. Proteomics also offers a window to study protein trafficking and routes of communication between organelles. Here, we summarize and discuss current progress in proteomics of the basal and specific host defense responses elicited by bacterial pathogens. PMID:22131803

  20. A silkworm model of pathogenic bacterial infection.

    PubMed

    Kaito, C; Sekimizu, K

    2007-10-01

    Silkworms are invertebrate animals that are killed by bacteria pathogenic against humans, such as Staphylococcus aureus, Streptococcus pyogenes, Pseudomonas aeruginosa, and Vibrio cholerae. Injection into the hemolymph of antibiotics that are clinically used for human patients abolishes the killing effects. There are several advantages to using silkworms as an infection model, such as low cost, the absence of ethical problems that are associated with the use of mammals, and a body size large enough to handle while injecting sample solution into the hemolymph. We screened S. aureus mutants with attenuated virulence against silkworms and found three novel virulence regulatory genes, cvfA, cvfB, and cvfC. These genes contribute to virulence against mice and are required for exotoxin production. The cvfA gene is required for expression of the agr locus, which regulates most exotoxin genes, and a novel DNA binding protein SarZ. Silkworms are susceptible to S. aureus beta toxin, P. aeruginosa exotoxin A, and diphtheria toxin. Therefore, silkworms are a promising infection model animal for the identification and evaluation of virulenceassociated genes.

  1. Lytic bacteriophages: Potential interventions against enteric bacterial pathogens on produce.

    PubMed

    Sharma, Manan

    2013-04-01

    Foodborne illnesses resulting from the consumption of produce commodities contaminated with enteric pathogens continue to be a significant public health issue. Lytic bacteriophages may provide an effective and natural intervention to reduce bacterial pathogens on fresh and fresh-cut produce commodities. The use of multi-phage cocktails specific for a single pathogen has been most frequently assessed on produce commodities to minimize the development of bacteriophage insensitive mutants (BIM) in target pathogen populations. Regulatory approval for the use of several lytic phage products specific for bacterial pathogens such as Escherichia coli O157:H7, Salmonella spp. and Listeria monocytogenes in foods and on food processing surfaces has been granted by various agencies in the US and other countries, possibly allowing for the more widespread use of bacteriophages in the decontamination of fresh and minimally processed produce. Research studies have shown lytic bacteriophages specific for E. coli O157:H7, Salmonella spp. and Listeria monocytogenes have been effective in reducing pathogen populations on leafy greens, sprouts and tomatoes.

  2. Ratiometric imaging of extracellular pH in bacterial biofilms with C-SNARF-4.

    PubMed

    Schlafer, Sebastian; Garcia, Javier E; Greve, Matilde; Raarup, Merete K; Nyvad, Bente; Dige, Irene

    2015-02-01

    pH in the extracellular matrix of bacterial biofilms is of central importance for microbial metabolism. Biofilms possess a complex three-dimensional architecture characterized by chemically different microenvironments in close proximity. For decades, pH measurements in biofilms have been limited to monitoring bulk pH with electrodes. Although pH microelectrodes with a better spatial resolution have been developed, they do not permit the monitoring of horizontal pH gradients in biofilms in real time. Quantitative fluorescence microscopy can overcome these problems, but none of the hitherto employed methods differentiated accurately between extracellular and intracellular microbial pH and visualized extracellular pH in all areas of the biofilms. Here, we developed a method to reliably monitor extracellular biofilm pH microscopically with the ratiometric pH-sensitive dye C-SNARF-4, choosing dental biofilms as an example. Fluorescent emissions of C-SNARF-4 can be used to calculate extracellular pH irrespective of the dye concentration. We showed that at pH values of <6, C-SNARF-4 stained 15 bacterial species frequently isolated from dental biofilm and visualized the entire bacterial biomass in in vivo-grown dental biofilms with unknown species composition. We then employed digital image analysis to remove the bacterial biomass from the microscopic images and adequately calculate extracellular pH values. As a proof of concept, we monitored the extracellular pH drop in in vivo-grown dental biofilms fermenting glucose. The combination of pH ratiometry with C-SNARF-4 and digital image analysis allows the accurate monitoring of extracellular pH in bacterial biofilms in three dimensions in real time and represents a significant improvement to previously employed methods of biofilm pH measurement.

  3. Within-host evolution decreases virulence in an opportunistic bacterial pathogen.

    PubMed

    Mikonranta, Lauri; Mappes, Johanna; Laakso, Jouni; Ketola, Tarmo

    2015-08-19

    Pathogens evolve in a close antagonistic relationship with their hosts. The conventional theory proposes that evolution of virulence is highly dependent on the efficiency of direct host-to-host transmission. Many opportunistic pathogens, however, are not strictly dependent on the hosts due to their ability to reproduce in the free-living environment. Therefore it is likely that conflicting selection pressures for growth and survival outside versus within the host, rather than transmission potential, shape the evolution of virulence in opportunists. We tested the role of within-host selection in evolution of virulence by letting a pathogen Serratia marcescens db11 sequentially infect Drosophila melanogaster hosts and then compared the virulence to strains that evolved only in the outside-host environment. We found that the pathogen adapted to both Drosophila melanogaster host and novel outside-host environment, leading to rapid evolutionary changes in the bacterial life-history traits including motility, in vitro growth rate, biomass yield, and secretion of extracellular proteases. Most significantly, selection within the host led to decreased virulence without decreased bacterial load while the selection lines in the outside-host environment maintained the same level of virulence with ancestral bacteria. This experimental evidence supports the idea that increased virulence is not an inevitable consequence of within-host adaptation even when the epidemiological restrictions are removed. Evolution of attenuated virulence could occur because of immune evasion within the host. Alternatively, rapid fluctuation between outside-host and within-host environments, which is typical for the life cycle of opportunistic bacterial pathogens, could lead to trade-offs that lower pathogen virulence.

  4. Genomic perspectives on the evolution and spread of bacterial pathogens

    PubMed Central

    Bentley, Stephen D.

    2015-01-01

    Since the first complete sequencing of a free-living organism, Haemophilus influenzae, genomics has been used to probe both the biology of bacterial pathogens and their evolution. Single-genome approaches provided information on the repertoire of virulence determinants and host-interaction factors, and, along with comparative analyses, allowed the proposal of hypotheses to explain the evolution of many of these traits. These analyses suggested many bacterial pathogens to be of relatively recent origin and identified genome degradation as a key aspect of host adaptation. The advent of very-high-throughput sequencing has allowed for detailed phylogenetic analysis of many important pathogens, revealing patterns of global and local spread, and recent evolution in response to pressure from therapeutics and the human immune system. Such analyses have shown that bacteria can evolve and transmit very rapidly, with emerging clones showing adaptation and global spread over years or decades. The resolution achieved with whole-genome sequencing has shown considerable benefits in clinical microbiology, enabling accurate outbreak tracking within hospitals and across continents. Continued large-scale sequencing promises many further insights into genetic determinants of drug resistance, virulence and transmission in bacterial pathogens. PMID:26702036

  5. Genomic perspectives on the evolution and spread of bacterial pathogens.

    PubMed

    Bentley, Stephen D; Parkhill, Julian

    2015-12-22

    Since the first complete sequencing of a free-living organism, Haemophilus influenzae, genomics has been used to probe both the biology of bacterial pathogens and their evolution. Single-genome approaches provided information on the repertoire of virulence determinants and host-interaction factors, and, along with comparative analyses, allowed the proposal of hypotheses to explain the evolution of many of these traits. These analyses suggested many bacterial pathogens to be of relatively recent origin and identified genome degradation as a key aspect of host adaptation. The advent of very-high-throughput sequencing has allowed for detailed phylogenetic analysis of many important pathogens, revealing patterns of global and local spread, and recent evolution in response to pressure from therapeutics and the human immune system. Such analyses have shown that bacteria can evolve and transmit very rapidly, with emerging clones showing adaptation and global spread over years or decades. The resolution achieved with whole-genome sequencing has shown considerable benefits in clinical microbiology, enabling accurate outbreak tracking within hospitals and across continents. Continued large-scale sequencing promises many further insights into genetic determinants of drug resistance, virulence and transmission in bacterial pathogens.

  6. Intra- and inter-species interactions within biofilms of important foodborne bacterial pathogens

    PubMed Central

    Giaouris, Efstathios; Heir, Even; Desvaux, Mickaël; Hébraud, Michel; Møretrø, Trond; Langsrud, Solveig; Doulgeraki, Agapi; Nychas, George-John; Kačániová, Miroslava; Czaczyk, Katarzyna; Ölmez, Hülya; Simões, Manuel

    2015-01-01

    A community-based sessile life style is the normal mode of growth and survival for many bacterial species. Under such conditions, cell-to-cell interactions are inevitable and ultimately lead to the establishment of dense, complex and highly structured biofilm populations encapsulated in a self-produced extracellular matrix and capable of coordinated and collective behavior. Remarkably, in food processing environments, a variety of different bacteria may attach to surfaces, survive, grow, and form biofilms. Salmonella enterica, Listeria monocytogenes, Escherichia coli, and Staphylococcus aureus are important bacterial pathogens commonly implicated in outbreaks of foodborne diseases, while all are known to be able to create biofilms on both abiotic and biotic surfaces. Particularly challenging is the attempt to understand the complexity of inter-bacterial interactions that can be encountered in such unwanted consortia, such as competitive and cooperative ones, together with their impact on the final outcome of these communities (e.g., maturation, physiology, antimicrobial resistance, virulence, dispersal). In this review, up-to-date data on both the intra- and inter-species interactions encountered in biofilms of these pathogens are presented. A better understanding of these interactions, both at molecular and biophysical levels, could lead to novel intervention strategies for controlling pathogenic biofilm formation in food processing environments and thus improve food safety. PMID:26347727

  7. Bacterial genome engineering and synthetic biology: combating pathogens.

    PubMed

    Krishnamurthy, Malathy; Moore, Richard T; Rajamani, Sathish; Panchal, Rekha G

    2016-11-04

    The emergence and prevalence of multidrug resistant (MDR) pathogenic bacteria poses a serious threat to human and animal health globally. Nosocomial infections and common ailments such as pneumonia, wound, urinary tract, and bloodstream infections are becoming more challenging to treat due to the rapid spread of MDR pathogenic bacteria. According to recent reports by the World Health Organization (WHO) and Centers for Disease Control and Prevention (CDC), there is an unprecedented increase in the occurrence of MDR infections worldwide. The rise in these infections has generated an economic strain worldwide, prompting the WHO to endorse a global action plan to improve awareness and understanding of antimicrobial resistance. This health crisis necessitates an immediate action to target the underlying mechanisms of drug resistance in bacteria. The advent of new bacterial genome engineering and synthetic biology (SB) tools is providing promising diagnostic and treatment plans to monitor and treat widespread recalcitrant bacterial infections. Key advances in genetic engineering approaches can successfully aid in targeting and editing pathogenic bacterial genomes for understanding and mitigating drug resistance mechanisms. In this review, we discuss the application of specific genome engineering and SB methods such as recombineering, clustered regularly interspaced short palindromic repeats (CRISPR), and bacterial cell-cell signaling mechanisms for pathogen targeting. The utility of these tools in developing antibacterial strategies such as novel antibiotic production, phage therapy, diagnostics and vaccine production to name a few, are also highlighted. The prevalent use of antibiotics and the spread of MDR bacteria raise the prospect of a post-antibiotic era, which underscores the need for developing novel therapeutics to target MDR pathogens. The development of enabling SB technologies offers promising solutions to deliver safe and effective antibacterial therapies.

  8. Antibiotic Capture by Bacterial Lipocalins Uncovers an Extracellular Mechanism of Intrinsic Antibiotic Resistance

    PubMed Central

    El-Halfawy, Omar M.; Klett, Javier; Ingram, Rebecca J.; Loutet, Slade A.; Murphy, Michael E. P.; Martín-Santamaría, Sonsoles

    2017-01-01

    ABSTRACT The potential for microbes to overcome antibiotics of different classes before they reach bacterial cells is largely unexplored. Here we show that a soluble bacterial lipocalin produced by Burkholderia cenocepacia upon exposure to sublethal antibiotic concentrations increases resistance to diverse antibiotics in vitro and in vivo. These phenotypes were recapitulated by heterologous expression in B. cenocepacia of lipocalin genes from Pseudomonas aeruginosa, Mycobacterium tuberculosis, and methicillin-resistant Staphylococcus aureus. Purified lipocalin bound different classes of bactericidal antibiotics and contributed to bacterial survival in vivo. Experimental and X-ray crystal structure-guided computational studies revealed that lipocalins counteract antibiotic action by capturing antibiotics in the extracellular space. We also demonstrated that fat-soluble vitamins prevent antibiotic capture by binding bacterial lipocalin with higher affinity than antibiotics. Therefore, bacterial lipocalins contribute to antimicrobial resistance by capturing diverse antibiotics in the extracellular space at the site of infection, which can be counteracted by known vitamins. PMID:28292982

  9. Detection of Foodborne Bacterial Pathogens from Individual Filth Flies

    PubMed Central

    Pava-Ripoll, Monica; Pearson, Rachel E.G.; Miller, Amy K.; Ziobro, George C.

    2015-01-01

    There is unanimous consensus that insects are important vectors of foodborne pathogens. However, linking insects as vectors of the pathogen causing a particular foodborne illness outbreak has been challenging. This is because insects are not being aseptically collected as part of an environmental sampling program during foodborne outbreak investigations and because there is not a standardized method to detect foodborne bacteria from individual insects. To take a step towards solving this problem, we adapted a protocol from a commercially available PCR-based system that detects foodborne pathogens from food and environmental samples, to detect foodborne pathogens from individual flies.Using this standardized protocol, we surveyed 100 wild-caught flies for the presence of Cronobacter spp., Salmonella enterica, and Listeria monocytogenes and demonstrated that it was possible to detect and further isolate these pathogens from the body surface and the alimentary canal of a single fly. Twenty-two percent of the alimentary canals and 8% of the body surfaces from collected wild flies were positive for at least one of the three foodborne pathogens. The prevalence of Cronobacter spp. on either body part of the flies was statistically higher (19%) than the prevalence of S. enterica (7%) and L.monocytogenes (4%). No false positives were observed when detecting S. enterica and L. monocytogenes using this PCR-based system because pure bacterial cultures were obtained from all PCR-positive results. However, pure Cronobacter colonies were not obtained from about 50% of PCR-positive samples, suggesting that the PCR-based detection system for this pathogen cross-reacts with other Enterobacteriaceae present among the highly complex microbiota carried by wild flies. The standardized protocol presented here will allow laboratories to detect bacterial foodborne pathogens from aseptically collected insects, thereby giving public health officials another line of evidence to find out how

  10. Detection of foodborne bacterial pathogens from individual filth flies.

    PubMed

    Pava-Ripoll, Monica; Pearson, Rachel E G; Miller, Amy K; Ziobro, George C

    2015-02-13

    There is unanimous consensus that insects are important vectors of foodborne pathogens. However, linking insects as vectors of the pathogen causing a particular foodborne illness outbreak has been challenging. This is because insects are not being aseptically collected as part of an environmental sampling program during foodborne outbreak investigations and because there is not a standardized method to detect foodborne bacteria from individual insects. To take a step towards solving this problem, we adapted a protocol from a commercially available PCR-based system that detects foodborne pathogens from food and environmental samples, to detect foodborne pathogens from individual flies.Using this standardized protocol, we surveyed 100 wild-caught flies for the presence of Cronobacter spp., Salmonella enterica, and Listeria monocytogenes and demonstrated that it was possible to detect and further isolate these pathogens from the body surface and the alimentary canal of a single fly. Twenty-two percent of the alimentary canals and 8% of the body surfaces from collected wild flies were positive for at least one of the three foodborne pathogens. The prevalence of Cronobacter spp. on either body part of the flies was statistically higher (19%) than the prevalence of S. enterica (7%) and L.monocytogenes (4%). No false positives were observed when detecting S. enterica and L. monocytogenes using this PCR-based system because pure bacterial cultures were obtained from all PCR-positive results. However, pure Cronobacter colonies were not obtained from about 50% of PCR-positive samples, suggesting that the PCR-based detection system for this pathogen cross-reacts with other Enterobacteriaceae present among the highly complex microbiota carried by wild flies. The standardized protocol presented here will allow laboratories to detect bacterial foodborne pathogens from aseptically collected insects, thereby giving public health officials another line of evidence to find out how

  11. Systemic acquired tolerance to virulent bacterial pathogens in tomato.

    PubMed

    Block, Anna; Schmelz, Eric; O'Donnell, Phillip J; Jones, Jeffrey B; Klee, Harry J

    2005-07-01

    Recent studies on the interactions between plants and pathogenic microorganisms indicate that the processes of disease symptom development and pathogen growth can be uncoupled. Thus, in many instances, the symptoms associated with disease represent an active host response to the presence of a pathogen. These host responses are frequently mediated by phytohormones. For example, ethylene and salicylic acid (SA) mediate symptom development but do not influence bacterial growth in the interaction between tomato (Lycopersicon esculentum) and virulent Xanthomonas campestris pv vesicatoria (Xcv). It is not apparent why extensive tissue death is integral to a defense response if it does not have the effect of limiting pathogen proliferation. One possible function for this hormone-mediated response is to induce a systemic defense response. We therefore assessed the systemic responses of tomato to Xcv. SA- and ethylene-deficient transgenic lines were used to investigate the roles of these phytohormones in systemic signaling. Virulent and avirulent Xcv did induce a systemic response as evidenced by expression of defense-associated pathogenesis-related genes in an ethylene- and SA-dependent manner. This systemic response reduced cell death but not bacterial growth during subsequent challenge with virulent Xcv. This systemic acquired tolerance (SAT) consists of reduced tissue damage in response to secondary challenge with a virulent pathogen with no effect upon pathogen growth. SAT was associated with a rapid ethylene and pathogenesis-related gene induction upon challenge. SAT was also induced by infection with Pseudomonas syringae pv tomato. These data show that SAT resembles systemic acquired resistance without inhibition of pathogen growth.

  12. Systemic Acquired Tolerance to Virulent Bacterial Pathogens in Tomato1

    PubMed Central

    Block, Anna; Schmelz, Eric; O'Donnell, Phillip J.; Jones, Jeffrey B.; Klee, Harry J.

    2005-01-01

    Recent studies on the interactions between plants and pathogenic microorganisms indicate that the processes of disease symptom development and pathogen growth can be uncoupled. Thus, in many instances, the symptoms associated with disease represent an active host response to the presence of a pathogen. These host responses are frequently mediated by phytohormones. For example, ethylene and salicylic acid (SA) mediate symptom development but do not influence bacterial growth in the interaction between tomato (Lycopersicon esculentum) and virulent Xanthomonas campestris pv vesicatoria (Xcv). It is not apparent why extensive tissue death is integral to a defense response if it does not have the effect of limiting pathogen proliferation. One possible function for this hormone-mediated response is to induce a systemic defense response. We therefore assessed the systemic responses of tomato to Xcv. SA- and ethylene-deficient transgenic lines were used to investigate the roles of these phytohormones in systemic signaling. Virulent and avirulent Xcv did induce a systemic response as evidenced by expression of defense-associated pathogenesis-related genes in an ethylene- and SA-dependent manner. This systemic response reduced cell death but not bacterial growth during subsequent challenge with virulent Xcv. This systemic acquired tolerance (SAT) consists of reduced tissue damage in response to secondary challenge with a virulent pathogen with no effect upon pathogen growth. SAT was associated with a rapid ethylene and pathogenesis-related gene induction upon challenge. SAT was also induced by infection with Pseudomonas syringae pv tomato. These data show that SAT resembles systemic acquired resistance without inhibition of pathogen growth. PMID:15937273

  13. Importance of prophages to evolution and virulence of bacterial pathogens

    PubMed Central

    Fortier, Louis-Charles; Sekulovic, Ognjen

    2013-01-01

    Bacteriophages, or simply phages, are viruses infecting bacteria. With an estimated 1031 particles in the biosphere, phages outnumber bacteria by a factor of at least 10 and not surprisingly, they influence the evolution of most bacterial species, sometimes in unexpected ways. “Temperate” phages have the ability to integrate into the chromosome of their host upon infection, where they can reside as “quiescent” prophages until conditions favor their reactivation. Lysogenic conversion resulting from the integration of prophages encoding powerful toxins is probably the most determinant contribution of prophages to the evolution of pathogenic bacteria. We currently grasp only a small fraction of the total phage diversity. Phage biologists keep unraveling novel mechanisms developed by phages to parasitize their host. The purpose of this review is to give an overview of some of the various ways by which prophages change the lifestyle and boost virulence of some of the most dangerous bacterial pathogens. PMID:23611873

  14. The genome sequence of Xanthomonas oryzae pathovar oryzae KACC10331, the bacterial blight pathogen of rice

    PubMed Central

    Lee, Byoung-Moo; Park, Young-Jin; Park, Dong-Suk; Kang, Hee-Wan; Kim, Jeong-Gu; Song, Eun-Sung; Park, In-Cheol; Yoon, Ung-Han; Hahn, Jang-Ho; Koo, Bon-Sung; Lee, Gil-Bok; Kim, Hyungtae; Park, Hyun-Seok; Yoon, Kyong-Oh; Kim, Jeong-Hyun; Jung, Chol-hee; Koh, Nae-Hyung; Seo, Jeong-Sun; Go, Seung-Joo

    2005-01-01

    The nucleotide sequence was determined for the genome of Xanthomonas oryzae pathovar oryzae (Xoo) KACC10331, a bacterium that causes bacterial blight in rice (Oryza sativa L.). The genome is comprised of a single, 4 941 439 bp, circular chromosome that is G + C rich (63.7%). The genome includes 4637 open reading frames (ORFs) of which 3340 (72.0%) could be assigned putative function. Orthologs for 80% of the predicted Xoo genes were found in the previously reported X.axonopodis pv. citri (Xac) and X.campestris pv. campestris (Xcc) genomes, but 245 genes apparently specific to Xoo were identified. Xoo genes likely to be associated with pathogenesis include eight with similarity to Xanthomonas avirulence (avr) genes, a set of hypersensitive reaction and pathogenicity (hrp) genes, genes for exopolysaccharide production, and genes encoding extracellular plant cell wall-degrading enzymes. The presence of these genes provides insights into the interactions of this pathogen with its gramineous host. PMID:15673718

  15. Human Pathogens Abundant in the Bacterial Metagenome of Cigarettes

    PubMed Central

    Sapkota, Amy R.; Berger, Sibel; Vogel, Timothy M.

    2010-01-01

    Background Many studies have evaluated chemical, heavy metal, and other abiotic substances present in cigarettes and their roles in the development of lung cancer and other diseases, yet no studies have comprehensively evaluated bacterial diversity of cigarettes and the possible impacts of these microbes on respiratory illnesses in smokers and exposed nonsmokers. Objectives The goal of this study was to explore the bacterial metagenomes of commercially available cigarettes. Methods A 16S rRNA-based taxonomic microarray and cloning and sequencing were used to evaluate total bacterial diversity of four brands of cigarettes. Normalized microarray data were compared using principal component analysis and hierarchical cluster analysis to evaluate potential differences in microbial diversity across cigarette brands. Results Fifteen different classes of bacteria and a broad range of potentially pathogenic organisms were detected in all cigarette samples. Most notably, we detected Acinetobacter, Bacillus, Burkholderia, Clostridium, Klebsiella, Pseudomonas aeruginosa, and Serratia in ≥ 90% of all cigarette samples. Other pathogenic bacteria detected included Campylobacter, Enterococcus, Proteus, and Staphylococcus. No significant variability in bacterial diversity was observed across the four different cigarette brands. Conclusions Previous studies have shown that smoking is associated with colonization by pathogenic bacteria and an increased risk of lung infections. However, this is the first study to show that cigarettes themselves could be the direct source of exposure to a wide array of potentially pathogenic microbes among smokers and other people exposed to secondhand smoke. The overall public health implications of these findings are unclear at this time, and future studies are necessary to determine whether bacteria in cigarettes could play important roles in the development of both infectious and chronic respiratory diseases. PMID:20064769

  16. Aptamer-assisted novel technologies for detecting bacterial pathogens.

    PubMed

    Alizadeh, Naser; Memar, Mohammad Yousef; Moaddab, Seyyed Reza; Kafil, Hossein Samadi

    2017-09-01

    Nowadays, all people are at risk of infectious diseases that are mainly caused by bacteria causing infection. There is a permanent demand for an appropriate detection method that is affordable, practical, careful, rapid, sensitive, efficient and economical. Aptamers are single stranded DNA or RNA oligonucleotides, which can be recognized specifically and bind to their target molecules and also, be exploited in diagnostic applications. Recently, aptamer-based systems have offered great potentials in applications for the recognition of several important bacterial pathogens from clinical and food specimens. There are several reports appraising the diagnostic applicability of aptamer-based systems for the detection of pathogens. As for its excellent sensitivity, as well as its rapid and efficient detectability, this technique may be practical to indicate bacterial targets with less sample size and may consume less time than traditional methods These systems offer a promising approach for the sensitive and quick detection of food-borne and clinical agents. This review provides an overview of aptamer-based methods as a novel approach for detecting bacterial pathogens. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  17. Genome-based approaches to develop vaccines against bacterial pathogens.

    PubMed

    Serruto, Davide; Serino, Laura; Masignani, Vega; Pizza, Mariagrazia

    2009-05-26

    Bacterial infectious diseases remain the single most important threat to health worldwide. Although conventional vaccinology approaches were successful in conferring protection against several diseases, they failed to provide efficacious solutions against many others. The advent of whole-genome sequencing changed the way to think about vaccine development, enabling the targeting of possible vaccine candidates starting from the genomic information of a single bacterial isolate, with a process named reverse vaccinology. As the genomic era progressed, reverse vaccinology has evolved with a pan-genome approach and multi-strain genome analysis became fundamental for the design of universal vaccines. This review describes the applications of genome-based approaches in the development of new vaccines against bacterial pathogens.

  18. Investigation of magnetic microdiscs for bacterial pathogen detection

    NASA Astrophysics Data System (ADS)

    Castillo-Torres, Keisha Y.; Garraud, Nicolas; Arnold, David P.; McLamore, Eric S.

    2016-05-01

    Despite strict regulations to control the presence of human pathogens in our food supply, recent foodborne outbreaks have heightened public concern about food safety and created urgency to improve methods for pathogen detection. Herein we explore a potentially portable, low-cost system that uses magnetic microdiscs for the detection of bacterial pathogens in liquid samples. The system operates by optically measuring the rotational dynamics of suspended magnetic microdiscs functionalized with pathogen-binding aptamers. The soft ferromagnetic (Ni80Fe20) microdiscs exhibit a closed magnetic spin arrangement (i.e. spin vortex) with zero magnetic stray field, leading to no disc agglomeration when in free suspension. With very high surface area for functionalization and volumes 10,000x larger than commonly used superparamagnetic nanoparticles, these 1.5-μm-diameter microdiscs are well suited for tagging, trapping, actuating, or interrogating bacterial targets. This work reports a wafer-level microfabrication process for fabrication of 600 million magnetic microdiscs per substrate and measurement of their rotational dynamics response. Additionally, the biofunctionalization of the microdiscs with DNA aptamers, subsequent binding to E. coli bacteria, and their magnetic manipulation is reported.

  19. Cutaneous bacterial species from Lithobates catesbeianus can inhibit pathogenic dermatophytes.

    PubMed

    Lauer, Antje; Hernandez, Trang

    2015-04-01

    Antibiotics are being successfully used to fight many infectious diseases caused by pathogenic microorganisms. However, new infectious diseases are continuously being identified, and some known pathogens are becoming resistant against known antibiotics. Furthermore, many antifungals are causing serious side effects in long-term treatments of patients, and many skin infections caused by dermatophytes are difficult to cure. The beneficial roles of resident cutaneous microbiota to inhibit pathogenic microorganisms have been shown for many vertebrate species. Microbial symbionts on the amphibian skin for example can be a source of powerful antimicrobial metabolites that can protect amphibians against diseases, such as chytridiomycosis, caused by a fungal pathogen. In this research, we investigated whether cutaneous bacterial species isolated from Lithobates catesbeianus (North American bullfrog), an invasive amphibian species that is resistant to chytridiomycosis, produce secondary metabolites that can be used to inhibit the growth of three species of dermatophytes (Microsporum gypseum, Epidermophyton floccosum, and Trichophyton mentagrophytes) which are known to cause topical or subdermal skin infections in humans. Strongly anti-dermatophyte bacterial species that belonged to the Bacillaceae, Streptomycetaceae, Pseudomonadaceae, Xanthomonadaceae, Aeromonadaceae, and Enterobacteriaceae were identified. This research has provided evidence of the presence of cutaneous anti-dermatophyte bacteria from L. catesbeianus which might provide a basis for health care providers to experiment with new antifungals in the future.

  20. Point detection of bacterial and viral pathogens using oral samples

    NASA Astrophysics Data System (ADS)

    Malamud, Daniel

    2008-04-01

    Oral samples, including saliva, offer an attractive alternative to serum or urine for diagnostic testing. This is particularly true for point-of-use detection systems. The various types of oral samples that have been reported in the literature are presented here along with the wide variety of analytes that have been measured in saliva and other oral samples. The paper focuses on utilizing point-detection of infectious disease agents, and presents work from our group on a rapid test for multiple bacterial and viral pathogens by monitoring a series of targets. It is thus possible in a single oral sample to identify multiple pathogens based on specific antigens, nucleic acids, and host antibodies to those pathogens. The value of such a technology for detecting agents of bioterrorism at remote sites is discussed.

  1. Antibiotic Capture by Bacterial Lipocalins Uncovers an Extracellular Mechanism of Intrinsic Antibiotic Resistance.

    PubMed

    El-Halfawy, Omar M; Klett, Javier; Ingram, Rebecca J; Loutet, Slade A; Murphy, Michael E P; Martín-Santamaría, Sonsoles; Valvano, Miguel A

    2017-03-14

    The potential for microbes to overcome antibiotics of different classes before they reach bacterial cells is largely unexplored. Here we show that a soluble bacterial lipocalin produced by Burkholderia cenocepacia upon exposure to sublethal antibiotic concentrations increases resistance to diverse antibiotics in vitro and in vivo These phenotypes were recapitulated by heterologous expression in B. cenocepacia of lipocalin genes from Pseudomonas aeruginosa, Mycobacterium tuberculosis, and methicillin-resistant Staphylococcus aureus Purified lipocalin bound different classes of bactericidal antibiotics and contributed to bacterial survival in vivo Experimental and X-ray crystal structure-guided computational studies revealed that lipocalins counteract antibiotic action by capturing antibiotics in the extracellular space. We also demonstrated that fat-soluble vitamins prevent antibiotic capture by binding bacterial lipocalin with higher affinity than antibiotics. Therefore, bacterial lipocalins contribute to antimicrobial resistance by capturing diverse antibiotics in the extracellular space at the site of infection, which can be counteracted by known vitamins.IMPORTANCE Current research on antibiotic action and resistance focuses on targeting essential functions within bacterial cells. We discovered a previously unrecognized mode of general bacterial antibiotic resistance operating in the extracellular space, which depends on bacterial protein molecules called lipocalins. These molecules are highly conserved in most bacteria and have the ability to capture different classes of antibiotics outside bacterial cells. We also discovered that liposoluble vitamins, such as vitamin E, overcome in vitro and in vivo antibiotic resistance mediated by bacterial lipocalins, providing an unexpected new alternative to combat resistance by using this vitamin or its derivatives as antibiotic adjuvants.

  2. Extracellular matrix structure governs invasion resistance in bacterial biofilms

    PubMed Central

    Nadell, Carey D; Drescher, Knut; Wingreen, Ned S; Bassler, Bonnie L

    2015-01-01

    Many bacteria are highly adapted for life in communities, or biofilms. A defining feature of biofilms is the production of extracellular matrix that binds cells together. The biofilm matrix provides numerous fitness benefits, including protection from environmental stresses and enhanced nutrient availability. Here we investigate defense against biofilm invasion using the model bacterium Vibrio cholerae. We demonstrate that immotile cells, including those identical to the biofilm resident strain, are completely excluded from entry into resident biofilms. Motile cells can colonize and grow on the biofilm exterior, but are readily removed by shear forces. Protection from invasion into the biofilm interior is mediated by the secreted protein RbmA, which binds mother–daughter cell pairs to each other and to polysaccharide components of the matrix. RbmA, and the invasion protection it confers, strongly localize to the cell lineages that produce it. PMID:25603396

  3. Extracellular matrix structure governs invasion resistance in bacterial biofilms.

    PubMed

    Nadell, Carey D; Drescher, Knut; Wingreen, Ned S; Bassler, Bonnie L

    2015-08-01

    Many bacteria are highly adapted for life in communities, or biofilms. A defining feature of biofilms is the production of extracellular matrix that binds cells together. The biofilm matrix provides numerous fitness benefits, including protection from environmental stresses and enhanced nutrient availability. Here we investigate defense against biofilm invasion using the model bacterium Vibrio cholerae. We demonstrate that immotile cells, including those identical to the biofilm resident strain, are completely excluded from entry into resident biofilms. Motile cells can colonize and grow on the biofilm exterior, but are readily removed by shear forces. Protection from invasion into the biofilm interior is mediated by the secreted protein RbmA, which binds mother-daughter cell pairs to each other and to polysaccharide components of the matrix. RbmA, and the invasion protection it confers, strongly localize to the cell lineages that produce it.

  4. Survival of coliforms and bacterial pathogens within protozoa during chlorination.

    PubMed Central

    King, C H; Shotts, E B; Wooley, R E; Porter, K G

    1988-01-01

    The susceptibility of coliform bacteria and bacterial pathogens to free chlorine residuals was determined before and after incubation with amoebae and ciliate protozoa. Viability of bacteria was quantified to determine their resistance to free chlorine residuals when ingested by laboratory strains of Acanthamoeba castellanii and Tetrahymena pyriformis. Cocultures of bacteria and protozoa were incubated to facilitate ingestion of the bacteria and then were chlorinated, neutralized, and sonicated to release intracellular bacteria. Qualitative susceptibility of protozoan strains to free chlorine was also assessed. Protozoa were shown to survive and grow after exposure to levels of free chlorine residuals that killed free-living bacteria. Ingested coliforms Escherichia coli, Citrobacter freundii, Enterobacter agglomerans, Enterobacter cloacae, Klebsiella pneumoniae, and Klebsiella oxytoca and bacterial pathogens Salmonella typhimurium, Yersinia enterocolitica, Shigella sonnei, Legionella gormanii, and Campylobacter jejuni had increased resistance to free chlorine residuals. Bacteria could be cultured from within treated protozoans well after the time required for 99% inactivation of free-living cells. All bacterial pathogens were greater than 50-fold more resistant to free chlorine when ingested by T. pyriformis. Escherichia coli ingested by a Cyclidium sp., a ciliate isolated from a drinking water reservoir, were also shown to be more resistant to free chlorine. The mechanism that increased resistance appeared to be survival within protozoan cells. This study indicates that bacteria can survive ingestion by protozoa. This bacterium-protozoan association provides bacteria with increased resistance to free chlorine residuals which can lead to persistence of bacteria in chlorine-treated water. We propose that resistance to digestion by predatory protozoa was an evolutionary precursor of pathogenicity in bacteria and that today it is a mechanism for survival of fastidious

  5. Lipidomic Analysis of Extracellular Vesicles from the Pathogenic Phase of Paracoccidioides brasiliensis

    PubMed Central

    Longo, Larissa V. G.; Ganiko, Luciane; Lopes, Felipe G.; Matsuo, Alisson L.; Almeida, Igor C.; Puccia, Rosana

    2012-01-01

    Background Fungal extracellular vesicles are able to cross the cell wall and transport molecules that help in nutrient acquisition, cell defense, and modulation of the host defense machinery. Methodology/Principal Findings Here we present a detailed lipidomic analysis of extracellular vesicles released by Paracoccidioides brasiliensis at the yeast pathogenic phase. We compared data of two representative isolates, Pb3 and Pb18, which have distinct virulence profiles and phylogenetic background. Vesicle lipids were fractionated into different classes and analyzed by either electrospray ionization- or gas chromatography-mass spectrometry. We found two species of monohexosylceramide and 33 phospholipid species, including phosphatidylcholine, phosphatidylethanolamine, phosphatidic acid, phosphatidylserine, phosphatidylinositol, and phosphatidylglycerol. Among the phospholipid-bound fatty acids in extracellular vesicles, C181 predominated in Pb3, whereas C18:2 prevailed in Pb18. The prevalent sterol in Pb3 and Pb18 vesicles was brassicasterol, followed by ergosterol and lanosterol. Inter-isolate differences in sterol composition were observed, and also between extracellular vesicles and whole cells. Conclusions/Significance The extensive lipidomic analysis of extracellular vesicles from two P. brasiliensis isolates will help to understand the composition of these fungal components/organelles and will hopefully be useful to study their biogenesis and role in host-pathogen interactions. PMID:22745761

  6. Questions about the behaviour of bacterial pathogens in vivo.

    PubMed Central

    Smith, H

    2000-01-01

    Bacterial pathogens cause disease in man and animals. They have unique biological properties, which enable them to colonize mucous surfaces, penetrate them, grow in the environment of the host, inhibit or avoid host defences and damage the host. The bacterial products responsible for these five biological requirements are the determinants of pathogenicity (virulence determinants). Current knowledge comes from studies in vitro, but now interest is increasing in how bacteria behave and produce virulence determinants within the infected host. There are three aspects to elucidate: bacterial activities, the host factors that affect them and the metabolic interactions between the two. The first is relatively easy to accomplish and, recently, new methods for doing this have been devised. The second is not easy because of the complexity of the environment in vivo and its ever-changing face. Nevertheless, some information can be gained from the literature and by new methodology. The third aspect is very difficult to study effectively unless some events in vivo can be simulated in vitro. The objectives of the Discussion Meeting were to describe the new methods and to show how they, and conventional studies, are revealing the activities of bacterial pathogens in vivo. This paper sets the scene by raising some questions and suggesting, with examples, how they might be answered. Bacterial growth in vivo is the primary requirement for pathogenicity. Without growth, determinants of the other four requirements are not formed. Results from the new methods are underlining this point. The important questions are as follows. What is the pattern of a developing infection and the growth rates and population sizes of the bacteria at different stages? What nutrients are present in vivo and how do they change as infection progresses and relate to growth rates and population sizes? How are these nutrients metabolized and by what bacterial mechanisms? Which bacterial processes handle

  7. EST mining and functional expression assays identify extracellular effector proteins from the plant pathogen Phytophthora.

    PubMed

    Torto, Trudy A; Li, Shuang; Styer, Allison; Huitema, Edgar; Testa, Antonino; Gow, Neil A R; van West, Pieter; Kamoun, Sophien

    2003-07-01

    Plant pathogenic microbes have the remarkable ability to manipulate biochemical, physiological, and morphological processes in their host plants. These manipulations are achieved through a diverse array of effector molecules that can either promote infection or trigger defense responses. We describe a general functional genomics approach aimed at identifying extracellular effector proteins from plant pathogenic microorganisms by combining data mining of expressed sequence tags (ESTs) with virus-based high-throughput functional expression assays in plants. PexFinder, an algorithm for automated identification of extracellular proteins from EST data sets, was developed and applied to 2147 ESTs from the oomycete plant pathogen Phytophthora infestans. The program identified 261 ESTs (12.2%) corresponding to a set of 142 nonredundant Pex (Phytophthora extracellular protein) cDNAs. Of these, 78 (55%) Pex cDNAs were novel with no significant matches in public databases. Validation of PexFinder was performed using proteomic analysis of secreted protein of P. infestans. To identify which of the Pex cDNAs encode effector proteins that manipulate plant processes, high-throughput functional expression assays in plants were performed on 63 of the identified cDNAs using an Agrobacterium tumefaciens binary vector carrying the potato virus X (PVX) genome. This led to the discovery of two novel necrosis-inducing cDNAs, crn1 and crn2, encoding extracellular proteins that belong to a large and complex protein family in Phytophthora. Further characterization of the crn genes indicated that they are both expressed in P. infestans during colonization of the host plant tomato and that crn2 induced defense-response genes in tomato. Our results indicate that combining data mining using PexFinder with PVX-based functional assays can facilitate the discovery of novel pathogen effector proteins. In principle, this strategy can be applied to a variety of eukaryotic plant pathogens, including

  8. Antibiofilm activity of Dendrophthoe falcata against different bacterial pathogens.

    PubMed

    Karthikeyan, Alagarsamy; Rameshkumar, Ramakrishnan; Sivakumar, Nallusamy; Al Amri, Issa S; Karutha Pandian, Shunmugiah; Ramesh, Manikandan

    2012-12-01

    Dendrophthoe falcata is a hemiparasitic plant commonly used for ailments such as ulcers, asthma, impotence, paralysis, skin diseases, menstrual troubles, pulmonary tuberculosis, and wounds. In this context, the validations of the traditional claim that the leaf extract of D. falcata possesses antibiofilm and anti-quorum sensing activity against different bacterial pathogens were assessed. The bacterial biofilms were quantified by crystal violet staining. Among the 17 bacterial pathogens screened, the methanolic fraction of the leaf extract clearly demonstrated antibiofilm activity for Proteus mirabilis, Vibrio vulnificus, Aeromonas hydrophila, Shigella sonnei, Chromobacterium violaceum ATCC 12472, Vibrio parahaemolyticus, Vibrio harveyi, Vibrio alginolyticus, Vibrio cholerae, and Proteus vulgaris. At biofilm inhibitory concentrations, biofilm formation was reduced by up to 70-90 %. Furthermore, the potential quorum-sensing activity of the leaf extract was tested by agar well diffusion using Chromobacterium violaceum (ATCC 12472 & CV O26) reporter strains. The inhibition of violacein production may be due to direct or indirect interference on QS by active constituents or the interactive effect of different phytocompounds present in the extracts. This is the first report on antibiofilm and QS activity of D. falcata leaf extracts, signifying the scope for development of complementary medicine for biofilm-associated infections.

  9. Exploring the biochemistry at the extracellular redox frontier of bacterial mineral Fe(III) respiration

    SciTech Connect

    Richardson, David J.; Edwards, Marcus; White, Gaye F.; Baiden, Nanakow; Hartshorne, Robert S.; Fredrickson, Jim K.; Shi, Liang; Zachara, John M.; Gates, Andrew J.; Butt, Julea N.; Clarke, Thomas

    2012-06-01

    Many species of the bacterial Shewanella genus are notable for their ability to respire in anoxic environments utilizing insoluble minerals of Fe(III) and Mn(IV) as extracellular electron acceptors. In Shewanella oneidensis, the process is dependent on the decahaem electron-transport proteins that lie at the extracellular face of the outer membrane where they can contact the insoluble mineral substrates. These extracellular proteins are charged with electrons provided by an inter-membrane electron-transfer pathway that links the extracellular face of the outer membrane with the inner cytoplasmic membrane and thereby intracellular electron sources. In the present paper, we consider the common structural features of two of these outermembrane decahaem cytochromes, MtrC and MtrF, and bring this together with biochemical, spectroscopic and voltammetric data to identify common and distinct properties of these prototypical members of different clades of the outer-membrane decahaem cytochrome superfamily.

  10. Neutrophils of Scophthalmus maximus produce extracellular traps that capture bacteria and inhibit bacterial infection.

    PubMed

    Chi, Heng; Sun, Li

    2016-03-01

    Neutrophils constitute an essential part of the innate immune system. Recently, neutrophils have been found to produce a complex extracellular structure called neutrophil extracellular traps (NETs) that capture bacteria, fungi, and parasites. In fish, a few studies on NETs production have been reported, however, the function of fish NETs is unknown. In this study, we examined the ability of turbot (Scophthalmus maximus) neutrophils to produce NETs and investigated the effect of turbot NETs on bacterial infection. We found that upon lipopolysaccharides treatment, turbot head kidney neutrophils produced typical NETs structures that contained DNA and histones. Bacteria treatment also induced production of NETs, which in turn entrapped the bacterial cells and inhibited bacterial replication. Furthermore, when introduced into turbot, NETs-trapped bacteria exhibited significantly weakened ability of tissue dissemination and colonization. These results indicate for the first time that teleost NETs possess apparent antibacterial effect both in vitro and in vivo.

  11. Prevalence of bacterial pathogens causing ocular infections in South India.

    PubMed

    Ramesh, S; Ramakrishnan, R; Bharathi, M Jayahar; Amuthan, M; Viswanathan, S

    2010-01-01

    The eye may be infected from external sources or through intra-ocular invasion of micro-organisms carried by the blood stream. This study was undertaken to isolate and identify the specific bacterial pathogens causing ocular infections and to determine their in-vitro antibacterial susceptibilities to commonly used antibacterial agents. A retrospective analysis of all patients with clinically diagnosed bacterial ocular infections such as blepharitis, conjunctivitis, internal and external hordeolum, suppurative scleritis, canaliculitis, keratitis, dacryocystitis, preseptal cellulitis, endophthalmitis and panophthalmitis presenting between January 2005 and December 2005 was performed. Extra-ocular and intra-ocular specimens were collected and were subjected to direct microscopy and culture. A total of 756 patients with bacterial ocular infections were analyzed, of which 462(61%) eyes had adnexal bacterial infection, 217(28.7%) had corneal infection, 6 (0.8%) had scleral involvement and the remaining 71(9.39%) eyes had infection of the intra-ocular tissues. The predominant bacterial species isolated was S. aureus (195 of 776; 25%) followed by S. pneumoniae (169 of 776; 21.78%) and coagulase negative staphylococci (142 of 776; 18.3%). The largest number of gram-positive isolates were susceptible to cefazolin (545 of 624; 87.34%), chloramphenicol (522 of 624; 83.65%) and gatifloxacin (511 of 624; 81.89%) and gram-negative isolates were to amikacin (127 of 136; 93.38%), gatifloxacin (125 of 136; 91.91%) and ofloxacin (119 of 136; 87.5%), while aerobic actinomycetes were to amikacin (100%), gatifloxacin (14 of 16; 87.5%), chloramphenicol (14 of 16; 87.5%) and ofloxacin (13 of 16; 81.25%). S. aureus frequently causes infections of eyelids and conjunctiva, S. pneumoniae of lacrimal apparatus and cornea and coagulase negative staphylococci causes intra-ocular infections. Of all routinely used antibacterials tested, flouroquinolones, especially gatifloxacin and ofloxacin

  12. Active Transport of Phosphorylated Carbohydrates Promotes Intestinal Colonization and Transmission of a Bacterial Pathogen

    PubMed Central

    Sit, Brandon; Crowley, Shauna M.; Bhullar, Kirandeep; Lai, Christine Chieh-Lin; Tang, Calvin; Hooda, Yogesh; Calmettes, Charles; Khambati, Husain; Ma, Caixia; Brumell, John H.; Schryvers, Anthony B.; Vallance, Bruce A.; Moraes, Trevor F.

    2015-01-01

    Efficient acquisition of extracellular nutrients is essential for bacterial pathogenesis, however the identities and mechanisms for transport of many of these substrates remain unclear. Here, we investigate the predicted iron-binding transporter AfuABC and its role in bacterial pathogenesis in vivo. By crystallographic, biophysical and in vivo approaches, we show that AfuABC is in fact a cyclic hexose/heptose-phosphate transporter with high selectivity and specificity for a set of ubiquitous metabolites (glucose-6-phosphate, fructose-6-phosphate and sedoheptulose-7-phosphate). AfuABC is conserved across a wide range of bacterial genera, including the enteric pathogens EHEC O157:H7 and its murine-specific relative Citrobacter rodentium, where it lies adjacent to genes implicated in sugar sensing and acquisition. C. rodentium ΔafuA was significantly impaired in an in vivo murine competitive assay as well as its ability to transmit infection from an afflicted to a naïve murine host. Sugar-phosphates were present in normal and infected intestinal mucus and stool samples, indicating that these metabolites are available within the intestinal lumen for enteric bacteria to import during infection. Our study shows that AfuABC-dependent uptake of sugar-phosphates plays a critical role during enteric bacterial infection and uncovers previously unrecognized roles for these metabolites as important contributors to successful pathogenesis. PMID:26295949

  13. Bacterial iron-sulfur cluster sensors in mammalian pathogens

    PubMed Central

    Miller, Halie K.; Auerbuch, Victoria

    2015-01-01

    Iron-sulfur clusters act as important cofactors for a number of transcriptional regulators in bacteria, including many mammalian pathogens. The sensitivity of iron-sulfur clusters to iron availability, oxygen tension, and reactive oxygen and nitrogen species enables bacteria to use such regulators to adapt their gene expression profiles rapidly in response to changing environmental conditions. In this review, we discuss how the [4Fe-4S] or [2Fe-2S] cluster-containing regulators FNR, Wbl, aconitase, IscR, NsrR, SoxR, and AirSR contribute to bacterial pathogenesis through control of both metabolism and classical virulence factors. In addition, we briefly review mammalian iron homeostasis as well as oxidative/nitrosative stress to provide context for understanding the function of bacterial iron-sulfur cluster sensors in different niches within the host. PMID:25738802

  14. A single natural nucleotide mutation alters bacterial pathogen host tropism.

    PubMed

    Viana, David; Comos, María; McAdam, Paul R; Ward, Melissa J; Selva, Laura; Guinane, Caitriona M; González-Muñoz, Beatriz M; Tristan, Anne; Foster, Simon J; Fitzgerald, J Ross; Penadés, José R

    2015-04-01

    The capacity of microbial pathogens to alter their host tropism leading to epidemics in distinct host species populations is a global public and veterinary health concern. To investigate the molecular basis of a bacterial host-switching event in a tractable host species, we traced the evolutionary trajectory of the common rabbit clone of Staphylococcus aureus. We report that it evolved through a likely human-to-rabbit host jump over 40 years ago and that only a single naturally occurring nucleotide mutation was required and sufficient to convert a human-specific S. aureus strain into one that could infect rabbits. Related mutations were identified at the same locus in other rabbit strains of distinct clonal origin, consistent with convergent evolution. This first report of a single mutation that was sufficient to alter the host tropism of a microorganism during its evolution highlights the capacity of some pathogens to readily expand into new host species populations.

  15. A bacterial pathogen infecting gametophytes of Saccharina japonica (Laminariales, Phaeophyceae)

    NASA Astrophysics Data System (ADS)

    Peng, Yanting; Li, Wei

    2013-03-01

    A newly identified bacterial disease of kelp ( Saccharina japonica) gametophytes was found in clone cultures. It is characterized by swollen gametophyte cells in the early period of infection followed by filamentous fading. An alginolytic marine bacterium referred to as A-1 was isolated from the diseased gametophytes. On the basis of 16S rDNA sequencing and morphological, physiological and biochemical characteristics, the bacterium was identified as a strain of the genus Alteromonas. By testing Koch's postulates, Alteromonas sp. A-1 was further confirmed as the pathogen. The infection process was also investigated using both scanning electron and light microscopy.

  16. Microbiological food safety issues in Brazil: bacterial pathogens.

    PubMed

    Gomes, Bruna Carrer; Franco, Bernadette Dora Gombossy de Melo; De Martinis, Elaine Cristina Pereira

    2013-03-01

    The globalization of food supply impacts patterns of foodborne disease outbreaks worldwide, and consumers are having increased concern about microbiological food safety. In this sense, the assessment of epidemiological data of foodborne diseases in different countries has not only local impact, but it can also be of general interest, especially in the case of major global producers and exporters of several agricultural food products, such as Brazil. In this review, the most common agents of foodborne illnesses registered in Brazil will be presented, compiled mainly from official databases made available to the public. In addition, some representative examples of studies on foodborne bacterial pathogens commonly found in Brazilian foods are provided.

  17. Relationship between lactobacilli and opportunistic bacterial pathogens associated with vaginitis

    PubMed Central

    Razzak, Mohammad Sabri A.; Al-Charrakh, Alaa H.; AL-Greitty, Bara Hamid

    2011-01-01

    Background: Vaginitis, is an infectious inflammation of the vaginal mucosa, which sometimes involves the vulva. The balance of the vaginal flora is maintained by the Lactobacilli and its protective and probiotic role in treating and preventing vaginal infection by producing antagonizing compounds which are regarded as safe for humans. Aim: The aim of this study was to evaluate the protective role of Lactobacilli against common bacterial opportunistic pathogens in vaginitis and study the effects of some antibiotics on Lactobacilli isolates. Materials and Methods: In this study (110) vaginal swabs were obtained from women suffering from vaginitis who admitted to Babylon Hospital of Maternity and Paediatrics in Babylon province, Iraq. The study involved the role of intrauterine device among married women with vaginitis and also involved isolation of opportunistic bacterial isolates among pregnant and non pregnant women. This study also involved studying probiotic role of Lactobacilli by production of some defense factors like hydrogen peroxide, bacteriocin, and lactic acid. Results: Results revealed that a total of 130 bacterial isolates were obtained. Intrauterine device was a predisposing factor for vaginitis. The most common opportunistic bacterial isolates were Staphylococcus aureus, Escherichia coli, Streptococcus agalactiae, and Klebsiella pneumoniae. All Lactobacilli were hydrogen peroxide producers while some isolates were bacteriocin producers that inhibited some of opportunistic pathogens (S. aureus, E. coli). Lactobacilli were sensitive to erythromycin while 93.3% of them were resistant to ciprofloxacin and (40%, 53.3%) of them were resistant to amoxicillin and gentamycin respectively. Results revealed that there was an inverse relationship between Lactobacilli presence and organisms causing vaginitis. This may be attributed to the production of defense factors by Lactobacilli. Conclusion: The types of antibiotics used to treat vaginitis must be very

  18. Relationship between lactobacilli and opportunistic bacterial pathogens associated with vaginitis.

    PubMed

    Razzak, Mohammad Sabri A; Al-Charrakh, Alaa H; Al-Greitty, Bara Hamid

    2011-04-01

    Vaginitis, is an infectious inflammation of the vaginal mucosa, which sometimes involves the vulva. The balance of the vaginal flora is maintained by the Lactobacilli and its protective and probiotic role in treating and preventing vaginal infection by producing antagonizing compounds which are regarded as safe for humans. The aim of this study was to evaluate the protective role of Lactobacilli against common bacterial opportunistic pathogens in vaginitis and study the effects of some antibiotics on Lactobacilli isolates. In this study (110) vaginal swabs were obtained from women suffering from vaginitis who admitted to Babylon Hospital of Maternity and Paediatrics in Babylon province, Iraq. The study involved the role of intrauterine device among married women with vaginitis and also involved isolation of opportunistic bacterial isolates among pregnant and non pregnant women. This study also involved studying probiotic role of Lactobacilli by production of some defense factors like hydrogen peroxide, bacteriocin, and lactic acid. Results revealed that a total of 130 bacterial isolates were obtained. Intrauterine device was a predisposing factor for vaginitis. The most common opportunistic bacterial isolates were Staphylococcus aureus, Escherichia coli, Streptococcus agalactiae, and Klebsiella pneumoniae. All Lactobacilli were hydrogen peroxide producers while some isolates were bacteriocin producers that inhibited some of opportunistic pathogens (S. aureus, E. coli). Lactobacilli were sensitive to erythromycin while 93.3% of them were resistant to ciprofloxacin and (40%, 53.3%) of them were resistant to amoxicillin and gentamycin respectively. Results revealed that there was an inverse relationship between Lactobacilli presence and organisms causing vaginitis. This may be attributed to the production of defense factors by Lactobacilli. The types of antibiotics used to treat vaginitis must be very selective in order not to kill the beneficial bacteria

  19. Tick-borne bacterial pathogens in southwestern Finland.

    PubMed

    Sormunen, Jani J; Penttinen, Ritva; Klemola, Tero; Hänninen, Jari; Vuorinen, Ilppo; Laaksonen, Maija; Sääksjärvi, Ilari E; Ruohomäki, Kai; Vesterinen, Eero J

    2016-03-22

    Ixodes ricinus and Ixodes persulcatus are the main vectors of Lyme borreliosis spirochetes and several other zoonotic bacteria in northern Europe and Russia. However, few studies screening bacterial pathogens in Finnish ticks have been conducted. Therefore, reports on the occurrence and prevalence of several bacterial pathogens detected from ticks elsewhere in Europe and Russia are altogether missing from Finland. The main aim of the current study was to produce novel data on the occurrence and prevalence of several tick-borne bacterial pathogens in ticks collected from southwestern Finland. Ticks were collected in 2013-2014 by blanket dragging from 25 localities around southwestern Finland, and additionally from a dog in Lempäälä. Collected ticks were molecularly identified and screened for Borrelia burgdorferi s.l., Borrelia miyamotoi, Rickettsia, Bartonella and Candidatus Neoehrlichia mikurensis using quantitative PCR. Furthermore, detected Rickettsia spp. were sequenced using conventional PCR to determine species. A total of 3169 ticks in 1174 DNA samples were screened for the listed pathogens. The most common bacteria detected was B. burgdorferi (s.l.) (18.5 % nymphal and 23.5 % adult ticks), followed by Rickettsia spp. (1.1 %; 5.1 %) and B. miyamotoi (0.51 %; 1.02 %). B. miyamotoi and Rickettsia spp. were also detected in larval samples (minimum infection rates 0.31 % and 0.21 %, respectively). Detected Rickettsia spp. were identified by sequencing as R. helvetica and R. monacensis. All screened samples were negative for Bartonella spp. and Ca. N. mikurensis. In the current study we report for the first time the presence of Rickettsia in Finnish ticks. Furthermore, Rickettsia spp. and B. miyamotoi were found from larval tick samples, emphasizing the importance they may have as vectors of these pathogens. Comparisons of tick density estimates and B. burgdorferi (s.l.) prevalence made between the current study and a previous study conducted in 2000 in ten

  20. Critical-Point Drying: Rapid Method for the Determination of Bacterial Extracellular Polymer and Surface Structures

    PubMed Central

    Cagle, Gerald D.

    1974-01-01

    The relative amount of extracellular polymer which remains about Azotobacter vinelandii, Zoogloea ramigera, Klebsiella pneumoniae, and Diplococcus pneumoniae after critical-point drying was studied by electron microscopy. The results obtained with this technique are compared to those obtained with methods that illustrate extracellular polymer, such as freeze-etching and ruthenium red staining. Comparative results indicate critical-point drying to be a rapid, reliable method for the determination of capsule-like polymer surrounding bacterial cells. In addition, critical-point drying can be used to observe morphogenetic changes, such as vesicle production. Images PMID:4136617

  1. Bacterial Community Composition and Extracellular Enzyme Activity in Temperate Streambed Sediment during Drying and Rewetting

    PubMed Central

    Pohlon, Elisabeth; Ochoa Fandino, Adriana; Marxsen, Jürgen

    2013-01-01

    Droughts are among the most important disturbance events for stream ecosystems; they not only affect stream hydrology but also the stream biota. Although desiccation of streams is common in Mediterranean regions, phases of dryness in headwaters have been observed more often and for longer periods in extended temperate regions, including Central Europe, reflecting global climate change and enhanced water withdrawal. The effects of desiccation and rewetting on the bacterial community composition and extracellular enzyme activity, a key process in the carbon flow of streams and rivers, were investigated in a typical Central European stream, the Breitenbach (Hesse, Germany). Wet streambed sediment is an important habitat in streams. It was sampled and exposed in the laboratory to different drying scenarios (fast, intermediate, slow) for 13 weeks, followed by rewetting of the sediment from the fast drying scenario via a sediment core perfusion technique for 2 weeks. Bacterial community structure was analyzed using CARD-FISH and TGGE, and extracellular enzyme activity was assessed using fluorogenic model substrates. During desiccation the bacterial community composition shifted toward composition in soil, exhibiting increasing proportions of Actinobacteria and Alphaproteobacteria and decreasing proportions of Bacteroidetes and Betaproteobacteria. Simultaneously the activities of extracellular enzymes decreased, most pronounced with aminopeptidases and less pronounced with enzymes involved in the degradation of polymeric carbohydrates. After rewetting, the general ecosystem functioning, with respect to extracellular enzyme activity, recovered after 10 to 14 days. However, the bacterial community composition had not yet achieved its original composition as in unaffected sediments within this time. Thus, whether the bacterial community eventually recovers completely after these events remains unknown. Perhaps this community undergoes permanent changes, especially after

  2. Entry of the bacterial pathogen Listeria monocytogenes into mammalian cells.

    PubMed

    Ireton, Keith

    2007-06-01

    The bacterial pathogen Listeria monocytogenes causes food-borne illnesses leading to meningitis or abortion. Listeria provokes its internalization ('entry') into mammalian cells that are normally non-phagocytic, such as intestinal epithelial cells and hepatocytes. Entry provides access to a nutrient-rich cytosol and allows translocation across anatomical barriers. Here I discuss the two major internalization pathways used by Listeria. These pathways are initiated by binding of the bacterial surface proteins InlA or InlB to their respective host receptors, E-cadherin or Met. InlA mediates traversal of the intestinal barrier, whereas InlB promotes infection of the liver. At the cellular level, both InlA- and InlB-dependent entry require host signalling that promotes cytoskeletal rearrangements and pathogen engulfment. However, many of the specific signalling proteins in the two entry routes differ. InlA-mediated uptake uses components of adherens junctions that are coupled to F-actin and myosin, whereas InlB-dependent entry involves cytosolic adaptors that bridge Met to regulators of F-actin, including phosphoinositide 3-kinase and activators of the Arp2/3 complex. Unexpectedly, entry directed by InlB also involves endocytic components. Future work on InlA and InlB will lead to a better understanding of virulence, and may also provide novel insights into the normal biological functions of E-cadherin and Met.

  3. Human mesenchymal stem cells: New sojourn of bacterial pathogens.

    PubMed

    Kohli, Sakshi; Singh, Yadvir; Sowpati, Divya Tej; Ehtesham, Nasreen Z; Dobrindt, Ulrich; Hacker, Jörg; Hasnain, Seyed E

    2015-05-01

    Tuberculosis (TB), caused by Mycobacterium tuberculosis (M. tuberculosis), is the leading infectious disease which claims one human life every 15-20s globally. The persistence of this deadly disease in human population can be attributed to the ability of the bacterium to stay in latent form. M. tuberculosis possesses a plethora of mechanisms not only to survive latently under harsh conditions inside the host but also modulate the host immune cells in its favour. Various M. tuberculosis gene families have also been described to play a role in this process. Recently, human bone marrow derived mesenchymal stem cells (MSCs) have been reported as a niche for dormant M. tuberculosis. MSCs possess abilities to alter the host immune response. The bacterium finds this self-renewal and immune privileged nature of MSCs very favourable not only to modulate the host immune system, with some help from its own genes, but also to avoid the external drug pressure. We suggest that the MSCs not only provide a resting place for M. tuberculosis but could also, by virtue of their intrinsic ability to disseminate in the body, explain the genesis of extra-pulmonary TB. A similar exploitation of stem cells by other bacterial pathogens is a distinct possibility. It may be likely that other intracellular bacterial pathogens adopt this strategy to 'piggy-back' on to ovarian stem cells to ensure vertical transmission and successful propagation to the next generation. Copyright © 2015 Elsevier GmbH. All rights reserved.

  4. Gemini Cationic Amphiphiles Control Biofilm Formation by Bacterial Vaginosis Pathogens.

    PubMed

    Algburi, Ammar; Zhang, Yingyue; Weeks, Richard; Comito, Nicole; Zehm, Saskia; Pinto, Juanita; Uhrich, Kathryn E; Chikindas, Michael L

    2017-09-11

    Antibiotic resistance and recurrence of bacterial vaginosis (BV), a polymicrobial infection, justify the need for novel antimicrobials to counteract microbial resistance to conventional antibiotics. Previously, two series of cationic amphiphiles (CAms), which self-assemble into supramolecular nanostructures with membrane-lytic properties, were designed with hydrophilic head groups and non-polar domains. The combination of CAms with commonly prescribed antibiotics is suggested as a promising strategy for targeting microorganisms that are resistant to conventional antibiotics. Activity of the CAms against Gardnerella vaginalis ATCC 14018, a BV representative pathogen, ranged from 1.1 to 24.4 μM. Interestingly, the tested healthy Lactobacillus species, especially L. plantarum ATCC 39268, were significantly more tolerant to CAms compared to the selected pathogens. In addition, CAms prevented biofilm formation at concentrations which did not influence the normal growth ability of G. vaginalis ATCC 14018. Furthermore, the minimum biofilm bactericidal activity (MBC-B) of CAms against G. vaginalis ATCC 14018 ranged between 58.8 and 425.6 μM while much higher concentrations (≥850 μM) were required to produce ≥3 log reduction in the number of biofilm-associated lactobacilli. The conventional antibiotic metronidazole strongly synergized with all tested CAms against planktonic cells and biofilms of G. vaginalis ATCC 14018. The synergism between CAms and the tested conventional antibiotic may be considered a new, effective, and beneficial method of controlling biofilm-associated bacterial vaginosis. Copyright © 2017 American Society for Microbiology.

  5. Antimicrobial Resistance in Bacterial Poultry Pathogens: A Review

    PubMed Central

    Nhung, Nguyen Thi; Chansiripornchai, Niwat; Carrique-Mas, Juan J.

    2017-01-01

    monitor the evolution of AMR in poultry bacterial pathogens. PMID:28848739

  6. Antimicrobial Resistance in Bacterial Poultry Pathogens: A Review.

    PubMed

    Nhung, Nguyen Thi; Chansiripornchai, Niwat; Carrique-Mas, Juan J

    2017-01-01

    monitor the evolution of AMR in poultry bacterial pathogens.

  7. The Staphylococcus aureus extracellular adherence protein promotes bacterial internalization by keratinocytes independent of fibronectin-binding proteins.

    PubMed

    Bur, Stephanie; Preissner, Klaus T; Herrmann, Mathias; Bischoff, Markus

    2013-08-01

    Staphylococcus aureus, the leading causal pathogen of skin infections, is strongly associated with skin atopy, and a number of bacterial adhesins allow the microbe to adhere to and invade eukaryotic cells. One of these adhesive molecules is the multifunctional extracellular adherence protein (Eap), which is overexpressed in situ in authentic human wounds and was shown to delay wound healing in experimental models. Yet, its role during invasion of keratinocytes is not clearly defined. By using a gentamicin/lysostaphin protection assay we demonstrate here that preincubation of HaCaT cells or primary keratinocytes with Eap results in a concentration-dependent significant increase in staphylococcal adhesion, followed by an even more pronounced internalization of bacteria by eukaryotic cells. Flow cytometric analysis revealed that Eap increased both the number of infected eukaryotic cells and the bacterial load per infected cell. Moreover, treatment of keratinocytes with Eap strongly enhanced the internalization of coagulase-negative staphylococci, as well as of E. coli, and markedly promoted staphylococcal invasion into extended-culture keratinocytes, displaying expression of keratin 10 and involucrin as differentiation markers. Thus, wound-related staphylococcal Eap may provide a major cellular invasin function, thereby enhancing the pathogen's ability to hide from the host immune system during acute and chronic skin infection.

  8. Bacterial Pathogen Indicator Transport from Livestock Mortality Biopiles.

    PubMed

    Michitsch, Robert; Jamieson, Rob; Gordon, Robert; Stratton, Glenn; Lake, Craig

    2015-09-01

    Biopiles can be used to dispose of slaughterhouse residuals (SLRs); however, the fate of pathogenic bacteria (e.g., pathogenic strains of , ) in these systems is not well understood. The transport of these bacteria in water leaching from the biopile could represent a significant contamination source. This research examined the transport of Enterobacteriaceae and Enterococcaceae indicator bacteria from SLR biopiles. Three biopiles (2.6 m wide by 4.6 m long by 1.8 m high) were formed on soil layers in concrete cells that allowed for real-time monitoring of environmental parameters, hydrologic flux, and indicator bacteria levels in effluent leaching from the piles. In biopile effluent, indicator bacteria populations decreased exponentially following biopile formation. Indicator bacteria loads in effluent constituted <0.01% of the initial indicator bacteria levels in the biopiles, which was attributed to retention, inactivation, and death. Nearly 90% of the total indicator bacteria loads coincided with large precipitation events (>15 mm d). Movement of the indicator bacteria through the biopiles and underlying soil appeared to be consistent with preferential flow phenomena. The populations of the Enterobacteriaceae indicators remained low in conditions of higher soil water content and lower biopile temperatures, whereas the Enterococcaceae indicator appeared to regrow in these conditions. This indicated that bacterial pathogen transport from a biopile could be a concern after the disappearance of conventional bacterial indicators, such as . Management considerations should attempt to divert excess water from entering a biopile, such as locating a biopile under a roof. Unsaturated biopile and soil conditions should be maintained to impede water flow through preferential pathways in the soil underneath a biopile.

  9. Characterization of bacterial pathogens in rural and urban irrigation water.

    PubMed

    Aijuka, Matthew; Charimba, George; Hugo, Celia J; Buys, Elna M

    2015-03-01

    The study aimed to compare the bacteriological quality of an urban and rural irrigation water source. Bacterial counts, characterization, identification and diversity of aerobic bacteria were determined. Escherichia coli isolated from both sites was subjected to antibiotic susceptibility testing, virulence gene (Stx1/Stx2 and eae) determination and (GTG)5 Rep-PCR fingerprinting. Low mean monthly counts for aerobic spore formers, anaerobic spore formers and Staphylococcus aureus were noted although occasional spikes were observed. The most prevalent bacterial species at both sites were Bacillus spp., E. coli and Enterobacter spp. In addition, E. coli and Bacillus spp. were most prevalent in winter and summer respectively. Resistance to at least one antibiotic was 84% (rural) and 83% (urban). Highest resistance at both sites was to cephalothin and ampicillin. Prevalence of E. coli possessing at least one virulence gene (Stx1/Stx2 and eae) was 15% (rural) and 42% (urban). All (rural) and 80% (urban) of E. coli possessing virulence genes showed antibiotic resistance. Complete genetic relatedness (100%) was shown by 47% of rural and 67% of urban E. coli isolates. Results from this study show that surface irrigation water sources regardless of geographical location and surrounding land-use practices can be reservoirs of similar bacterial pathogens.

  10. Bithionol blocks pathogenicity of bacterial toxins, ricin, and Zika virus

    PubMed Central

    Leonardi, William; Zilbermintz, Leeor; Cheng, Luisa W.; Zozaya, Josue; Tran, Sharon H.; Elliott, Jeffrey H.; Polukhina, Kseniya; Manasherob, Robert; Li, Amy; Chi, Xiaoli; Gharaibeh, Dima; Kenny, Tara; Zamani, Rouzbeh; Soloveva, Veronica; Haddow, Andrew D.; Nasar, Farooq; Bavari, Sina; Bassik, Michael C.; Cohen, Stanley N.; Levitin, Anastasia; Martchenko, Mikhail

    2016-01-01

    Diverse pathogenic agents often utilize overlapping host networks, and hub proteins within these networks represent attractive targets for broad-spectrum drugs. Using bacterial toxins, we describe a new approach for discovering broad-spectrum therapies capable of inhibiting host proteins that mediate multiple pathogenic pathways. This approach can be widely used, as it combines genetic-based target identification with cell survival-based and protein function-based multiplex drug screens, and concurrently discovers therapeutic compounds and their protein targets. Using B-lymphoblastoid cells derived from the HapMap Project cohort of persons of African, European, and Asian ancestry we identified host caspases as hub proteins that mediate the lethality of multiple pathogenic agents. We discovered that an approved drug, Bithionol, inhibits host caspases and also reduces the detrimental effects of anthrax lethal toxin, diphtheria toxin, cholera toxin, Pseudomonas aeruginosa exotoxin A, Botulinum neurotoxin, ricin, and Zika virus. Our study reveals the practicality of identifying host proteins that mediate multiple disease pathways and discovering broad-spectrum therapies that target these hub proteins. PMID:27686742

  11. Quorum sensing and Bacterial Pathogenicity: From Molecules to Disease

    PubMed Central

    Deep, Antariksh; Chaudhary, Uma; Gupta, Varsha

    2011-01-01

    Quorum sensing in prokaryotic biology refers to the ability of a bacterium to sense information from other cells in the population when they reach a critical concentration (i.e. a Quorum) and communicate with them. The “language” used for this intercellular communication is based on small, self-generated signal molecules called as autoinducers. Quorum sensing is thought to afford pathogenic bacteriaa mechanism to minimize host immune responses by delaying theproduction of tissue-damaging virulence factors until sufficientbacteria have amassed and are prepared to overwhelm host defensemechanisms and establish infection. Quorum sensing systems are studied in a large number of gram-negative bacterial species belonging to α, β, and γ subclasses of proteobacteria. Among the pathogenic bacteria, Pseudomonas aeruginosa is perhaps the best understood in terms of the virulence factors regulated and the role the Quorum sensing plays in pathogenicity. Presently, Quorum sensing is considered as a potential novel target for antimicrobial therapy to control multi/all drug-resistant infections. This paper reviews Quorum sensing in gram positive and gram negative bacteria and its role in biofilm formation. PMID:21701655

  12. Quorum sensing and Bacterial Pathogenicity: From Molecules to Disease.

    PubMed

    Deep, Antariksh; Chaudhary, Uma; Gupta, Varsha

    2011-01-01

    Quorum sensing in prokaryotic biology refers to the ability of a bacterium to sense information from other cells in the population when they reach a critical concentration (i.e. a Quorum) and communicate with them. The "language" used for this intercellular communication is based on small, self-generated signal molecules called as autoinducers. Quorum sensing is thought to afford pathogenic bacteriaa mechanism to minimize host immune responses by delaying theproduction of tissue-damaging virulence factors until sufficientbacteria have amassed and are prepared to overwhelm host defensemechanisms and establish infection. Quorum sensing systems are studied in a large number of gram-negative bacterial species belonging to α, β, and γ subclasses of proteobacteria. Among the pathogenic bacteria, Pseudomonas aeruginosa is perhaps the best understood in terms of the virulence factors regulated and the role the Quorum sensing plays in pathogenicity. Presently, Quorum sensing is considered as a potential novel target for antimicrobial therapy to control multi/all drug-resistant infections. This paper reviews Quorum sensing in gram positive and gram negative bacteria and its role in biofilm formation.

  13. Meeting report: Adaptation and communication of bacterial pathogens.

    PubMed

    Aussel, Laurent; Beuzón, Carmen R; Cascales, Eric

    2016-05-18

    Bacteria usually live in complex environments, sharing niche and resources with other bacterial species, unicellular eukaryotic cells or complex organisms. Thus, they have evolved mechanisms to communicate, to compete and to adapt to changing environment as diverse as human tissues, animals or plants. Understanding the molecular mechanisms underlying these adaptation processes is therefore of primary importance for epidemiology and human health protection, and was the focus of a Current Trends in Biomedicine workshop organized by the International University of Andalucia in late October 2015 in Baeza (Spain). The topic was covered by complementary sessions: (i) interbacterial communication and competition that enable a better access to nutrients or a more efficient colonization of the ecological niche, (ii) adaptation of intracellular pathogens to their host, focusing on metabolic pathways, adaptive mechanisms and populational heterogeneity, and (iii) adaptation of animal and plant pathogens as well as plant-associated bacteria to a plant niche. This workshop emphasized the broad repertoire of mechanisms and factors bacteria have evolved to become efficient pathogens.

  14. Meeting report: Adaptation and communication of bacterial pathogens

    PubMed Central

    Aussel, Laurent; Beuzón, Carmen R.; Cascales, Eric

    2016-01-01

    ABSTRACT Bacteria usually live in complex environments, sharing niche and resources with other bacterial species, unicellular eukaryotic cells or complex organisms. Thus, they have evolved mechanisms to communicate, to compete and to adapt to changing environment as diverse as human tissues, animals or plants. Understanding the molecular mechanisms underlying these adaptation processes is therefore of primary importance for epidemiology and human health protection, and was the focus of a Current Trends in Biomedicine workshop organized by the International University of Andalucia in late October 2015 in Baeza (Spain). The topic was covered by complementary sessions: (i) interbacterial communication and competition that enable a better access to nutrients or a more efficient colonization of the ecological niche, (ii) adaptation of intracellular pathogens to their host, focusing on metabolic pathways, adaptive mechanisms and populational heterogeneity, and (iii) adaptation of animal and plant pathogens as well as plant-associated bacteria to a plant niche. This workshop emphasized the broad repertoire of mechanisms and factors bacteria have evolved to become efficient pathogens. PMID:26890494

  15. Bithionol blocks pathogenicity of bacterial toxins, ricin, and Zika virus.

    PubMed

    Leonardi, William; Zilbermintz, Leeor; Cheng, Luisa W; Zozaya, Josue; Tran, Sharon H; Elliott, Jeffrey H; Polukhina, Kseniya; Manasherob, Robert; Li, Amy; Chi, Xiaoli; Gharaibeh, Dima; Kenny, Tara; Zamani, Rouzbeh; Soloveva, Veronica; Haddow, Andrew D; Nasar, Farooq; Bavari, Sina; Bassik, Michael C; Cohen, Stanley N; Levitin, Anastasia; Martchenko, Mikhail

    2016-09-30

    Diverse pathogenic agents often utilize overlapping host networks, and hub proteins within these networks represent attractive targets for broad-spectrum drugs. Using bacterial toxins, we describe a new approach for discovering broad-spectrum therapies capable of inhibiting host proteins that mediate multiple pathogenic pathways. This approach can be widely used, as it combines genetic-based target identification with cell survival-based and protein function-based multiplex drug screens, and concurrently discovers therapeutic compounds and their protein targets. Using B-lymphoblastoid cells derived from the HapMap Project cohort of persons of African, European, and Asian ancestry we identified host caspases as hub proteins that mediate the lethality of multiple pathogenic agents. We discovered that an approved drug, Bithionol, inhibits host caspases and also reduces the detrimental effects of anthrax lethal toxin, diphtheria toxin, cholera toxin, Pseudomonas aeruginosa exotoxin A, Botulinum neurotoxin, ricin, and Zika virus. Our study reveals the practicality of identifying host proteins that mediate multiple disease pathways and discovering broad-spectrum therapies that target these hub proteins.

  16. Dexamethasone Inhibits S. aureus-Induced Neutrophil Extracellular Pathogen-Killing Mechanism, Possibly through Toll-Like Receptor Regulation.

    PubMed

    Wan, Ting; Zhao, Yingying; Fan, Fangli; Hu, Renjian; Jin, Xiuming

    2017-01-01

    Neutrophils release neutrophil extracellular traps (NETs) in a pathogen-killing process called NETosis. Excessive NETs formation, however, is implicated in disease pathogenesis. Therefore, to understand how NETosis is regulated, we examined the effect of dexamethasone (DXM), an anti-inflammatory drug, on this process and the role of toll-like receptors (TLRs). We stimulated human neutrophils with phorbol 12-myristate 13-acetate (PMA) or Staphylococcus aureus (S. aureus) and quantified NETs formation. We also examined the effect of DXM on the bactericidal effect of NETs and the role of reactive oxygen species (ROS) and nuclear factor (NF)-κB in DXM-regulated NETosis. DXM significantly inhibited S. aureus-induced NETosis and extracellular bacterial killing. ROS production and NF-κB activation were not involved in DXM-regulated NETosis. TLR2 and TLR4, but not TLR5 or TLR6, modified S. aureus-induced NETs formation. Neither DXM nor TLRs were involved in PMA-induced NETosis. Furthermore, TLR2 and TLR4 agonists rescued DXM-inhibited NETosis, and neither TLR2 nor TLR4 antagonists could further inhibit NETosis reduction induced by DXM, indicating that DXM may inhibit NETosis by regulating TLR2 and TLR4. In conclusion, the mechanisms of S. aureus- and PMA-induced NETosis are different. DXM decreases NETs formation independently of oxidant production and NF-κB phosphorylation and possibly via a TLR-dependent mechanism.

  17. Dexamethasone Inhibits S. aureus-Induced Neutrophil Extracellular Pathogen-Killing Mechanism, Possibly through Toll-Like Receptor Regulation

    PubMed Central

    Wan, Ting; Zhao, Yingying; Fan, Fangli; Hu, Renjian; Jin, Xiuming

    2017-01-01

    Neutrophils release neutrophil extracellular traps (NETs) in a pathogen-killing process called NETosis. Excessive NETs formation, however, is implicated in disease pathogenesis. Therefore, to understand how NETosis is regulated, we examined the effect of dexamethasone (DXM), an anti-inflammatory drug, on this process and the role of toll-like receptors (TLRs). We stimulated human neutrophils with phorbol 12-myristate 13-acetate (PMA) or Staphylococcus aureus (S. aureus) and quantified NETs formation. We also examined the effect of DXM on the bactericidal effect of NETs and the role of reactive oxygen species (ROS) and nuclear factor (NF)-κB in DXM-regulated NETosis. DXM significantly inhibited S. aureus-induced NETosis and extracellular bacterial killing. ROS production and NF-κB activation were not involved in DXM-regulated NETosis. TLR2 and TLR4, but not TLR5 or TLR6, modified S. aureus-induced NETs formation. Neither DXM nor TLRs were involved in PMA-induced NETosis. Furthermore, TLR2 and TLR4 agonists rescued DXM-inhibited NETosis, and neither TLR2 nor TLR4 antagonists could further inhibit NETosis reduction induced by DXM, indicating that DXM may inhibit NETosis by regulating TLR2 and TLR4. In conclusion, the mechanisms of S. aureus- and PMA-induced NETosis are different. DXM decreases NETs formation independently of oxidant production and NF-κB phosphorylation and possibly via a TLR-dependent mechanism. PMID:28232829

  18. Flocculation behaviour of hematite-kaolinite suspensions in presence of extracellular bacterial proteins and polysaccharides.

    PubMed

    Poorni, S; Natarajan, K A

    2014-02-01

    Cells of Bacillus subtilis exhibited higher affinity towards hematite than to kaolinite. Bacterial cells were grown and adapted in the presence of hematite and kaolinite. Higher amounts of mineral-specific proteinaceous compounds were secreted in the presence of kaolinite while hematite-grown cells produced higher amounts of exopolysaccharides. Extracellular proteins (EP) exhibited higher adsorption density on kaolinite which was rendered more hydrophobic. Hematite surfaces were rendered more hydrophilic due to increased adsorption of extracellular polysaccharides (ECP). Significant surface chemical changes were produced due to interaction between minerals and extracellular proteins and polysaccharides. Iron oxides such as hematite could be effectively removed from kaolinite clays using selective bioflocculation of hematite after interaction with EP and ECP extracted from mineral-grown cells.

  19. Mobilization of adsorbed copper and lead from naturally aged soil by bacterial extracellular polymers.

    PubMed

    Jensen-Spaulding, Anna; Shuler, Michael L; Lion, Leonard W

    2004-03-01

    Sorption of pollutants is a dominant phase transfer process affecting the fate and transport of metals through the subsurface. The movement of contaminants is retarded by sorption to the stationary subsurface porous media and can seriously hinder remediation efforts. Research has shown that the binding of adsorbed metals becomes more pronounced the longer the contaminant is in the subsurface and the release rates of aged metal contaminants have not received the research attention given to freshly added metals in laboratory studies. Metal release rates are also influenced by the presence of dissolved ligands that compete with mineral soil surfaces by providing binding sites. Dissolved organic matter such as bacterial extracellular polymers are common in natural soil solutions and the metal binding properties of bacterial polymers are well established. Therefore, binding of metals to dissolved biopolymers may result in mobilization of an adsorbed metal. This is important for cases where the metals are assumed to be relatively immobile such as in the case of land applied biosolids. In addition, naturally occurring adherent bacteria commonly produce extracellular polymers and thus may modify the bioavailability of meal contaminants at the point of their attachment. In this study samples from three sites, one a land applied sludge test site, were used to investigate the ability of bacterial extracellular polymers to release metals from soils with long-term exposures. The presence of ?200mg/L bacterial extracellular polymer was found to increase the short-term (less than 350h) release of Cu and Pb by a factor of 2-4-fold.

  20. Nano-TiO2 affects Cu speciation, extracellular enzyme activity, and bacterial communities in sediments.

    PubMed

    Fan, Wenhong; Liu, Tong; Li, Xiaomin; Peng, Ruishuang; Zhang, Yilin

    2016-11-01

    In aquatic ecosystems, titanium dioxide nanoparticles (nano-TiO2) coexist with heavy metals and influence the existing forms and toxicities of the metal in water. However, limited information is available regarding the ecological risk of this coexistence in sediments. In this study, the effect of nano-TiO2 on Cu speciation in sediments was investigated using sequential extraction. The microcosm approach was also employed to analyze the effects of the coexistence of nano-TiO2 and Cu on extracellular enzyme activity and bacterial communities in sediments. Results showed that nano-TiO2 decreased the organic matter-bound fraction of Cu and increased the corresponding residual fraction Cu. As a result, speciation of exogenous Cu in sediments changed. During the course of the 30-day experiment, the presence of nano-TiO2 did not affect Cu-induced changes in bacterial community structure. However, the coexistence of nano-TiO2 and Cu restrained the activity of bacterial extracellular enzymes, such as alkaline phosphatase and β-glucosidase. The degree of inhibition also varied because of the different properties of extracellular enzymes. This research highlighted the importance of understanding and predicting the effects of the coexistence of nanomaterials and other pollutants in sediments.

  1. Effects of bacterial cells and two types of extracellular polymers on bioclogging of sand columns

    NASA Astrophysics Data System (ADS)

    Xia, Lu; Zheng, Xilai; Shao, Haibing; Xin, Jia; Sun, Zhaoyue; Wang, Leyun

    2016-04-01

    Microbially induced reductions in the saturated hydraulic conductivity, Ks, of natural porous media, conventionally called bioclogging, occurs frequently in natural and engineered subsurface systems. Bioclogging can affect artificial groundwater recharge, in situ bioremediation of contaminated aquifers, or permeable reactive barriers. In this study, we designed a series of percolation experiments to simulate the growth and metabolism of bacteria in sand columns. The experimental results showed that the bacterial cell amount gradually increased to a maximum of 8.91 log10 CFU/g sand at 144 h during the bioclogging process, followed by a decrease to 7.89 log10 CFU/g sand until 336 h. The same variation pattern was found for the concentration of tightly bound extracellular polymeric substances (TB-EPS), which had a peak value of 220.76 μg/g sand at 144 h. In the same experiments, the concentration of loosely bound extracellular polymeric substances (LB-EPS) increased sharply from 54.45 to 575.57 μg/g sand in 192 h, followed by a slight decline to 505.04 μg/g sand. The increase of the bacterial cell amount along with the other two concentrations could reduce the Ks of porous media, but their relative contributions varied to a large degree during different percolation stages. At the beginning of the tests (e.g., 48 h before), bacterial cells were likely responsible for the Ks reduction of porous media because no increase was found for the other two concentrations. With the accumulation of cells and EPS production from 48 to 144 h, both were important for the reduction of Ks. However, in the late period of percolation tests from 144 to 192 h, LB-EPS was probably responsible for the further reduction of Ks, as the bacterial cell amount and TB-EPS concentration decreased. Quantitative contributions of bacterial cell amount and the two types of extracellular polymers to Ks reductions were also evaluated.

  2. Comparative analysis of glutaredoxin domains from bacterial opportunistic pathogens.

    PubMed

    Leeper, Thomas; Zhang, Suxin; Van Voorhis, Wesley C; Myler, Peter J; Varani, Gabriele

    2011-09-01

    Glutaredoxin proteins (GLXRs) are essential components of the glutathione system that reductively detoxify substances such as arsenic and peroxides and are important in the synthesis of DNA via ribonucleotide reductases. NMR solution structures of glutaredoxin domains from two Gram-negative opportunistic pathogens, Brucella melitensis and Bartonella henselae, are presented. These domains lack the N-terminal helix that is frequently present in eukaryotic GLXRs. The conserved active-site cysteines adopt canonical proline/tyrosine-stabilized geometries. A difference in the angle of α-helix 2 relative to the β-sheet surface and the presence of an extended loop in the human sequence suggests potential regulatory regions and/or protein-protein interaction motifs. This observation is consistent with mutations in this region that suppress defects in GLXR-ribonucleotide reductase interactions. These differences between the human and bacterial forms are adjacent to the dithiol active site and may permit species-selective drug design.

  3. Pathotypes of Bacterial Spot Pathogen Infecting Capsicum Peppers in Korea

    PubMed Central

    Wai, Khin Pa Pa; Siddique, Muhammad Irfan; Mo, Hwang-Sung; Yoo, Hee Ju; Byeon, Si-Eun; Jegal, Yoonhyuk; Mekuriaw, Alebel A.; Kim, Byung-Soo

    2015-01-01

    Sixty-seven isolates of bacterial spot pathogen (Xanthomonas spp.) collected from six provinces of Korea were tested for the identification of their pathotypes and determination of their distribution throughout Korea in an effort to genetically manage the disease. Near isogenic lines of Early Calwonder (Capsicum annuum) pepper plants carrying Bs1, Bs2 and Bs3, and PI235047 (C. pubescens) were used as differential hosts. Race P1 was found to be predominant, followed by race P7, and races P3 and P8 were also observed. This is the first report of races P7 and P8 in Korea. The races P7 and P8 were differentiated from the former races P1 and P3, respectively, on the basis of their ability to elicit hypersensitive reactions to PI235047. PMID:26674555

  4. Bacterial pathogens isolated from cultured bullfrogs (Rana castesbeiana).

    PubMed

    Mauel, Michael J; Miller, Debra L; Frazier, Kendall S; Hines, Murray E

    2002-09-01

    A commercial bullfrog (Rana castesbeiana) operation in south Georgia had multiple epizootics of systemic bacterial infections over a 3-year period, 1998-2000. A number of potential pathogens (Aeromonas hydrophila, Chryseobacterium (Flavobacterium) meningosepticum, Chryseobacterium (Flavobacterium) indolgenes, Edwardsiella tarda, Citrobacterfreundii, Pseudomonas spp., and (Streptococcus iniae) were isolated from various tissues. Clinically, frogs demonstrated acute onset of torticolis, stupor, and indifference to stimuli. Cutaneous hyperemia, subcutaneous and muscular hemorrhage, and peripheral edema were consistent gross findings. Histologically, clusters of lymphocytes, monocytes, and occasional acidophiles with scattered granulomas occurred in liver, kidney, and spleen. This is the first report of S. inae and C. meningosepticum as potential disease agents in R. castesbeiana. These findings suggest that a variety of bacteria may be associated with redleg and that culture results must be obtained for accurate diagnosis.

  5. Rapid SNP Detection and Genotyping of Bacterial Pathogens by Pyrosequencing.

    PubMed

    Amoako, Kingsley K; Thomas, Matthew C; Janzen, Timothy W; Goji, Noriko

    2017-01-01

    Bacterial identification and typing are fixtures of microbiology laboratories and are vital aspects of our response mechanisms in the event of foodborne outbreaks and bioterrorist events. Whole genome sequencing (WGS) is leading the way in terms of expanding our ability to identify and characterize bacteria through the identification of subtle differences between genomes (e.g. single nucleotide polymorphisms (SNPs) and insertions/deletions). Modern high-throughput technologies such as pyrosequencing can facilitate the typing of bacteria by generating short-read sequence data of informative regions identified by WGS analyses, at a fraction of the cost of WGS. Thus, pyrosequencing systems remain a valuable asset in the laboratory today. Presented in this chapter are two methods developed in the Amoako laboratory that detail the identification and genotyping of bacterial pathogens. The first targets canonical single nucleotide polymorphisms (canSNPs) of evolutionary importance in Bacillus anthracis, the causative agent of Anthrax. The second assay detects Shiga-toxin (stx) genes, which are associated with virulence in Escherichia coli and Shigella spp., and differentiates the subtypes of stx-1 and stx-2 based on SNP loci. These rapid methods provide end users with important information regarding virulence traits as well as the evolutionary and biogeographic origin of isolates.

  6. Removal of pathogenic bacterial biofilms by combinations of oxidizing compounds.

    PubMed

    Olmedo, Gabriela María; Grillo-Puertas, Mariana; Cerioni, Luciana; Rapisarda, Viviana Andrea; Volentini, Sabrina Inés

    2015-05-01

    Bacterial biofilms are commonly formed on medical devices and food processing surfaces. The antimicrobials used have limited efficacy against the biofilms; therefore, new strategies to prevent and remove these structures are needed. Here, the effectiveness of brief oxidative treatments, based on the combination of sodium hypochlorite (NaClO) and hydrogen peroxide (H2O2) in the presence of copper sulfate (CuSO4), were evaluated against bacterial laboratory strains and clinical isolates, both in planktonic and biofilm states. Simultaneous application of oxidants synergistically inactivated planktonic cells and prevented biofilm formation of laboratory Escherichia coli, Salmonella enterica serovar Typhimurium, Klebsiella pneumoniae, and Staphylococcus aureus strains, as well as clinical isolates of Salmonella enterica subsp. enterica, Klebsiella oxytoca, and uropathogenic E. coli. In addition, preformed biofilms of E. coli C, Salmonella Typhimurium, K. pneumoniae, and Salmonella enterica exposed to treatments were removed by applying 12 mg/L NaClO, 0.1 mmol/L CuSO4, and 350 mmol/L H2O2 for 5 min. Klebsiella oxytoca and Staphylococcus aureus required a 5-fold increase in NaClO concentration, and the E. coli clinical isolate remained unremovable unless treatments were applied on biofilms formed within 24 h instead of 48 h. The application of treatments that last a few minutes using oxidizing compounds at low concentrations represents an interesting disinfection strategy against pathogens associated with medical and industrial settings.

  7. Comparative analysis of two emerging rice seed bacterial pathogens.

    PubMed

    Fory, P A; Triplett, L; Ballen, C; Abello, J F; Duitama, J; Aricapa, M G; Prado, G A; Correa, F; Hamilton, J; Leach, J E; Tohme, J; Mosquera, G M

    2014-05-01

    Seed sterility and grain discoloration limit rice production in Colombia and several Central American countries. In samples of discolored rice seed grown in Colombian fields, the species Burkholderia glumae and B. gladioli were isolated, and field isolates were compared phenotypically. An artificial inoculation assay was used to determine that, although both bacterial species cause symptoms on rice grains, B. glumae is a more aggressive pathogen, causing yield reduction and higher levels of grain sterility. To identify putative virulence genes differing between B. glumae and B. gladioli, four previously sequenced genomes of Asian and U.S. strains of the two pathogens were compared with each other and with two draft genomes of Colombian B. glumae and B. gladioli isolates generated for this study. Whereas previously characterized Burkholderia virulence factors are highly conserved between the two species, B. glumae and B. gladioli strains are predicted to encode distinct groups of genes encoding type VI secretion systems, transcriptional regulators, and membrane-sensing proteins. This study shows that both B. glumae and B. gladioli can threaten grain quality, although only one species affects yield. Furthermore, genotypic differences between the two strains are identified that could contribute to disease phenotypic differences.

  8. The bacterial pathogen-ubiquitin interface: lessons learned from Shigella.

    PubMed

    Tanner, Kaitlyn; Brzovic, Peter; Rohde, John R

    2015-01-01

    Shigella species are the aetiological agents of shigellosis, a severe diarrhoeal disease that is a significant cause of morbidity and mortality worldwide. Shigellosis causes massive colonic destruction, high fever and bloody diarrhoea. Shigella pathogenesis is tightly linked to the ability of the bacterium to invade and replicate intracellularly within the colonic epithelium. Shigella uses a type 3 secretion system to deliver its effector proteins into the cytosol of infected cells. Among the repertoire of Shigella effectors, many are known to target components of the actin cytoskeleton to promote bacterial entry. An emerging alternate theme for effector function is the targeting of the host ubiquitin system. Ubiquitination is a post-translational modification restricted to eukaryotes and is involved in many essential host processes. By virtue of sheer number of ubiquitin-modulating effector proteins, it is clear that Shigella has invested heavily into subversion of the ubiquitin system. Understanding these host-pathogen interactions will inform us about the strategies used by successful pathogens and may also provide avenues for novel antimicrobial strategies.

  9. Influence of Calcium in Extracellular DNA Mediated Bacterial Aggregation and Biofilm Formation

    PubMed Central

    Koop, Leena; Wong, Yie Kuan; Ahmed, Safia; Siddiqui, Khawar Sohail; Manefield, Mike

    2014-01-01

    Calcium (Ca2+) has an important structural role in guaranteeing the integrity of the outer lipopolysaccharide layer and cell walls of bacterial cells. Extracellular DNA (eDNA) being part of the slimy matrix produced by bacteria promotes biofilm formation through enhanced structural integrity of the matrix. Here, the concurrent role of Ca2+ and eDNA in mediating bacterial aggregation and biofilm formation was studied for the first time using a variety of bacterial strains and the thermodynamics of DNA to Ca2+ binding. It was found that the eDNA concentrations under both planktonic and biofilm growth conditions were different among bacterial strains. Whilst Ca2+ had no influence on eDNA release, presence of eDNA by itself favours bacterial aggregation via attractive acid-base interactions in addition, its binding with Ca2+ at biologically relevant concentrations was shown further increase in bacterial aggregation via cationic bridging. Negative Gibbs free energy (ΔG) values in iTC data confirmed that the interaction between DNA and Ca2+ is thermodynamically favourable and that the binding process is spontaneous and exothermic owing to its highly negative enthalpy. Removal of eDNA through DNase I treatment revealed that Ca2+ alone did not enhance cell aggregation and biofilm formation. This discovery signifies the importance of eDNA and concludes that existence of eDNA on bacterial cell surfaces is a key facilitator in binding of Ca2+ to eDNA thereby mediating bacterial aggregation and biofilm formation. PMID:24651318

  10. Influence of calcium in extracellular DNA mediated bacterial aggregation and biofilm formation.

    PubMed

    Das, Theerthankar; Sehar, Shama; Koop, Leena; Wong, Yie Kuan; Ahmed, Safia; Siddiqui, Khawar Sohail; Manefield, Mike

    2014-01-01

    Calcium (Ca(2+)) has an important structural role in guaranteeing the integrity of the outer lipopolysaccharide layer and cell walls of bacterial cells. Extracellular DNA (eDNA) being part of the slimy matrix produced by bacteria promotes biofilm formation through enhanced structural integrity of the matrix. Here, the concurrent role of Ca(2+) and eDNA in mediating bacterial aggregation and biofilm formation was studied for the first time using a variety of bacterial strains and the thermodynamics of DNA to Ca(2+) binding. It was found that the eDNA concentrations under both planktonic and biofilm growth conditions were different among bacterial strains. Whilst Ca(2+) had no influence on eDNA release, presence of eDNA by itself favours bacterial aggregation via attractive acid-base interactions in addition, its binding with Ca(2+) at biologically relevant concentrations was shown further increase in bacterial aggregation via cationic bridging. Negative Gibbs free energy (ΔG) values in iTC data confirmed that the interaction between DNA and Ca(2+) is thermodynamically favourable and that the binding process is spontaneous and exothermic owing to its highly negative enthalpy. Removal of eDNA through DNase I treatment revealed that Ca(2+) alone did not enhance cell aggregation and biofilm formation. This discovery signifies the importance of eDNA and concludes that existence of eDNA on bacterial cell surfaces is a key facilitator in binding of Ca(2+) to eDNA thereby mediating bacterial aggregation and biofilm formation.

  11. Production of extracellular material by streptococci associated with subacute bacterial endocarditis.

    PubMed Central

    Straus, D C; Mattingly, S J; Milligan, T W

    1977-01-01

    Six strains of viridans streptococci isolated from confirmed cases of subacute bacterial endocarditis were studied for production of extracellular material. All six strains, when grown to the exponential phase, produced exoproducts that had similar elution profiles on a G-100 Sephadex column. Since essential nutrients, such as amino acids, may be periodically growth limiting to streptococci in the fibrin-covered lesions on heart valves, the potential to elaborate extracellular protein and other material by streptococci that were deprived of essential amino acids was studied. Examination of supernatant fluids from cultures of Streptococcus MG intermedius deprived of glutamate and cystine revealed the presence of a complex mixture of extracellular materials in amounts comparable to those produced by normallly growing cells, Although only a slight (21 to 24%) increase in total protein occurred during amino acid deprivation of 12 h, the extracellular material contained numerous protein components, several of which demonstrated proteolytic activity. On a cell dry weight basis, the amino acid-deprived cells produced four-to eightfold more protease(s) than did exponential cells grown in complete medium. These results demonstrate that viridans streptococci are capable of elaborating potentially damaging compounds even when their multiplication has been arrested by nutritional deprivation. Images PMID:885611

  12. Extracellular enzyme activity in anaerobic bacterial cultures: evidence of pullulanase activity among mesophilic marine bacteria.

    PubMed Central

    Arnosti, C; Repeta, D J

    1994-01-01

    The extracellular enzymatic activity of a mixed culture of anaerobic marine bacteria enriched on pullulan [alpha(1,6)-linked maltotriose units] was directly assessed with a combination of gel permeation chromatography (GPC) and nuclear magnetic resonance spectroscopy (NMR). Hydrolysis products of pullulan were separated by GPC into three fractions with molecular weights of > or = 10,000, approximately 5,000, and < or = 1,200. NMR spectra of these fractions demonstrated that pullulan was rapidly and specifically hydrolyzed at alpha(1,6) linkages by pullulanase enzymes, most likely type II pullulanase. Although isolated pullulanase enzymes have been shown to hydrolyze pullulan completely to maltotriose (S. H. Brown, H. R. Costantino, and R. M. Kelly, Appl. Environ. Microbiol. 56:1985-1991, 1990; M. Klingeberg, H. Hippe, and G. Antranikian, FEMS Microbiol. Lett. 69:145-152, 1990; R. Koch, P. Zablowski, A. Spreinat, and G. Antranikian, FEMS Microbiol. Lett. 71:21-26, 1990), the smallest carbohydrate detected in the bacterial cultures consisted of two maltotriose units linked through one alpha(1,6) linkage. Either the final hydrolysis step was closely linked to substrate uptake, or specialized porins similar to maltoporin might permit direct transport of large oligosaccharides into the bacterial cell. This is the first report of pullulanase activity among mesophilic marine bacteria. The combination of GPC and NMR could easily be used to assess other types of extracellular enzyme activity in bacterial cultures. PMID:8161177

  13. The pepper extracellular peroxidase CaPO2 is required for salt, drought and oxidative stress tolerance as well as resistance to fungal pathogens.

    PubMed

    Choi, Hyong Woo; Hwang, Byung Kook

    2012-06-01

    In plants, biotic and abiotic stresses regulate the expression and activity of various peroxidase isoforms. Capsicum annuum EXTRACELLULAR PEROXIDASE 2 (CaPO2) was previously shown to play a role in local and systemic reactive oxygen species bursts and disease resistance during bacterial pathogen infection. Here, we report CaPO2 expression patterns and functions during conditions of biotic and abiotic stress. In pepper plants, CaPO2 expression was strongly induced by abscisic acid, but not by defense-related plant hormones such as salicylic acid, ethylene and jasmonic acid. CaPO2 was also strongly induced by abiotic and biotic stress treatments, including drought, cold, high salinity and infection by the hemibiotrophic fungal pathogen Colletotrichum coccodes. Loss-of-function of CaPO2 in virus-induced gene silenced pepper plants led to increased susceptibility to salt- and osmotic-induced stress. In contrast, CaPO2 overexpression in transgenic Arabidopsis thaliana plants conferred enhanced tolerance to high salt, drought, and oxidative stress, while also enhancing resistance to infection by the necrotrophic fungal pathogen Alternaria brassicicola. Taken together, these results provide evidence for the involvement of pepper extracellular peroxidase CaPO2 in plant defense responses to various abiotic stresses and plant fungal pathogens.

  14. Trophic network architecture of root-associated bacterial communities determines pathogen invasion and plant health

    PubMed Central

    Wei, Zhong; Yang, Tianjie; Friman, Ville-Petri; Xu, Yangchun; Shen, Qirong; Jousset, Alexandre

    2015-01-01

    Host-associated bacterial communities can function as an important line of defence against pathogens in animals and plants. Empirical evidence and theoretical predictions suggest that species-rich communities are more resistant to pathogen invasions. Yet, the underlying mechanisms are unclear. Here, we experimentally test how the underlying resource competition networks of resident bacterial communities affect invasion resistance to the plant pathogen Ralstonia solanacearum in microcosms and in tomato plant rhizosphere. We find that bipartite resource competition networks are better predictors of invasion resistance compared with resident community diversity. Specifically, communities with a combination of stabilizing configurations (low nestedness and high connectance), and a clear niche overlap with the pathogen, reduce pathogen invasion success, constrain pathogen growth within invaded communities and have lower levels of diseased plants in greenhouse experiments. Bacterial resource competition network characteristics can thus be important in explaining positive diversity–invasion resistance relationships in bacterial rhizosphere communities. PMID:26400552

  15. Trophic network architecture of root-associated bacterial communities determines pathogen invasion and plant health.

    PubMed

    Wei, Zhong; Yang, Tianjie; Friman, Ville-Petri; Xu, Yangchun; Shen, Qirong; Jousset, Alexandre

    2015-09-24

    Host-associated bacterial communities can function as an important line of defence against pathogens in animals and plants. Empirical evidence and theoretical predictions suggest that species-rich communities are more resistant to pathogen invasions. Yet, the underlying mechanisms are unclear. Here, we experimentally test how the underlying resource competition networks of resident bacterial communities affect invasion resistance to the plant pathogen Ralstonia solanacearum in microcosms and in tomato plant rhizosphere. We find that bipartite resource competition networks are better predictors of invasion resistance compared with resident community diversity. Specifically, communities with a combination of stabilizing configurations (low nestedness and high connectance), and a clear niche overlap with the pathogen, reduce pathogen invasion success, constrain pathogen growth within invaded communities and have lower levels of diseased plants in greenhouse experiments. Bacterial resource competition network characteristics can thus be important in explaining positive diversity-invasion resistance relationships in bacterial rhizosphere communities.

  16. Hijacking Host Cell Highways: Manipulation of the Host Actin Cytoskeleton by Obligate Intracellular Bacterial Pathogens.

    PubMed

    Colonne, Punsiri M; Winchell, Caylin G; Voth, Daniel E

    2016-01-01

    Intracellular bacterial pathogens replicate within eukaryotic cells and display unique adaptations that support key infection events including invasion, replication, immune evasion, and dissemination. From invasion to dissemination, all stages of the intracellular bacterial life cycle share the same three-dimensional cytosolic space containing the host cytoskeleton. For successful infection and replication, many pathogens hijack the cytoskeleton using effector proteins introduced into the host cytosol by specialized secretion systems. A subset of effectors contains eukaryotic-like motifs that mimic host proteins to exploit signaling and modify specific cytoskeletal components such as actin and microtubules. Cytoskeletal rearrangement promotes numerous events that are beneficial to the pathogen, including internalization of bacteria, structural support for bacteria-containing vacuoles, altered vesicular trafficking, actin-dependent bacterial movement, and pathogen dissemination. This review highlights a diverse group of obligate intracellular bacterial pathogens that manipulate the host cytoskeleton to thrive within eukaryotic cells and discusses underlying molecular mechanisms that promote these dynamic host-pathogen interactions.

  17. Pathogenic Naegleria fowleri and non-pathogenic Naegleria lovaniensis exhibit differential adhesion to, and invasion of, extracellular matrix proteins

    PubMed Central

    Jamerson, Melissa; da Rocha-Azevedo, Bruno; Cabral, Guy A.

    2012-01-01

    Naegleria fowleri and Naegleria lovaniensis are closely related free-living amoebae found in the environment. N. fowleri causes primary amoebic meningoencephalitis (PAM), a rapidly fatal disease of the central nervous system, while N. lovaniensis is non-pathogenic. N. fowleri infection occurs when the amoebae access the nasal passages, attach to the nasal mucosa and its epithelial lining, and migrate to the brain. This process involves interaction with components of the host extracellular matrix (ECM). Since the ability to invade tissues can be a characteristic that distinguishes pathogenic from non-pathogenic amoebae, the objective of this study was to assess adhesion to, and invasion of, the ECM by these two related but distinct Naegleria species. N. fowleri exhibited a higher level of adhesion to the ECM components laminin-1, fibronectin and collagen I. Scanning electron microscopy revealed that N. fowleri attached on ECM substrata exhibited a spread-out appearance that included the presence of focal adhesion-like structures. Western immunoblotting revealed two integrin-like proteins for both species, but one of these, with a molecular mass of approximately 70 kDa, was detected at a higher level in N. fowleri. Confocal microscopy indicated that the integrin-like proteins co-localized to the focal adhesion-like structures. Furthermore, anti-integrin antibody decreased adhesion of N. fowleri to ECM components. Finally, N. fowleri disrupted 3D ECM scaffolds, while N. lovaniensis had a minimal effect. Collectively, these results indicate a distinction in adhesion to, and invasion of, ECM proteins between N. fowleri and N. lovaniensis. PMID:22222499

  18. [Bacterial enteric pathogens' resistance to fluoroquinolones and last generation cephalosporines].

    PubMed

    Damian, Maria; Usein, Codruţa-Romanita; Palade, Andi Marian; Băltoiu, Mădălina; Condei, Maria; Ciontea, Simona; Tatu-Chiţoiu, Dorina

    2010-01-01

    The increase of incidence of resistance to the antibiotics became the most worrisome subject within the clinical and research communities in the medical fields. Intrinsic resistance genetic mutations, horizontal transfer of mobile structures carrying genes coding for resistance to the antibiotics within the pan-microbial genome are representing the bacterial resistome which is bearing the genetic information regarding the defensive mechanisms developed by micro-organisms to protect themselves against antibiotics. Rice in the resistance of enteric bacteria, pathogens involved in a large number of human infections, to the cephalosporin of last generation and to the fluoroquinolones is a very actual subject in the medical area. Production of beta-lactamases with extended spectrum is the most important enzymatic defence system, developed by micro-organisms, consisting in the inactivation of beta-lactam antibiotics by destroying the beta-lactam ring. Enterobacteria are able to produce beta-lactamases of type TEM, SHV and/or CTX-M. Punctual mutations in nucleotide structure of bla genes, coding for beta-lactamases synthesis, are leading on production of a large diversity of enzymes with enlarged spectrum of activity (ESBL). At the beginning of 90's the first beta-lactamases resistance to clavulanic acid were detected and in our days more then 170 TEM, 120 SVH and 90 CTX-MESBLs are known. Escherichia coli strains are producing, firstly, TEM ESBLs, Klebsiella pneumoniae SHV ESBLs. and both are producing CTX-M type ESBLs, are resistant to the fluoroquinolones due to punctual mutations in nucleotide structure of gyr gene coding for gyrases production, enzymes involved in nucleic acids replication. Resistance to the antibiotics with extended activity is a public health threat due to their capacity of large spreading within bacterial population, when the coding structures are located on mobile genetic structures. The menace increase when genes coding for fluoroquinolones

  19. Mediterranean Fruit Fly as a Potential Vector of Bacterial Pathogens

    PubMed Central

    Sela, Shlomo; Nestel, David; Pinto, Riky; Nemny-Lavy, Esther; Bar-Joseph, Moshe

    2005-01-01

    The Mediterranean fruit fly (Ceratitis capitata) is a cosmopolitan pest of hundreds of species of commercial and wild fruits. It is considered a major economic pest of commercial fruits in the world. Adult Mediterranean fruit flies feed on all sorts of protein sources, including animal excreta, in order to develop eggs. After reaching sexual maturity and copulating, female flies lay eggs in fruit by puncturing the skin with their ovipositors and injecting batches of eggs into the wounds. In view of the increase in food-borne illnesses associated with consumption of fresh produce and unpasteurized fruit juices, we investigated the potential of Mediterranean fruit fly to serve as a vector for transmission of human pathogens to fruits. Addition of green fluorescent protein (GFP)-tagged Escherichia coli to a Mediterranean fruit fly feeding solution resulted in a dose-dependent increase in the fly's bacterial load. Flies exposed to fecal material enriched with GFP-tagged E. coli were similarly contaminated and were capable of transmitting E. coli to intact apples in a cage model system. Washing contaminated apples with tap water did not eliminate the E. coli. Flies inoculated with E. coli harbored the bacteria for up to 7 days following contamination. Fluorescence microscopy demonstrated that the majority of fluorescent bacteria were confined along the pseudotrachea in the labelum edge of the fly proboscis. Wild flies captured at various geographic locations were found to carry coliforms, and in some cases presumptive identification of E. coli was made. These findings support the hypothesis that the common Mediterranean fruit fly is a potential vector of human pathogens to fruits. PMID:16000820

  20. Optimising methodology for determining the effect of ocean acidification on bacterial extracellular enzymes

    NASA Astrophysics Data System (ADS)

    Burrell, T. J.; Maas, E. W.; Teesdale-Spittle, P.; Law, C. S.

    2015-04-01

    To fully understand the impact of ocean acidification on biogeochemical cycles, the response of bacterial extracellular enzymes needs to be considered as they play a central role in the degradation and distribution of labile organic matter. This study investigates the methodology, and potential artefacts involved in determining the response of bacterial extracellular glucosidase and protease to ocean acidification. The effect of pH on artificial fluorophores and substrates was examined, as well as the impact of three different acidification methods. The results indicate that pH has a significant effect on the fluorescence of the artificial fluorophore 4-methylumbeliferone for glucosidase activity, and 7-amino-4-methylcoumarin for protease activity, while artificial aminopeptidase substrate alters the pH of seawater, confirming previous observations. Before use in ocean acidification research these enzyme assay components must be buffered in order to stabilise sample pH. Reduction of coastal seawater pH to 7.8 was shown to increase β-glucosidase activity rapidly (0.5 h), while no significant response was detected for leucine aminopeptidase, highlighting the need for short-term direct effects of pH on enzyme activities. Bubbling with CO2 gas resulted in higher β-glucosidase activity when compared to acidification using gas-permeable silicon tubing and acidification with HCl. Although bubbling showed variable effects between two experiments conducted at different times of the year. In addition, bacterial cell numbers were 15-40% higher with bubbling relative to seawater acidified with gas-permeable silicon tubing and HCl. Artefacts associated with bubbling may lead to the overestimation of extracellular enzyme activities, and interpretation of the impacts of ocean acidification on organic matter cycling.

  1. Assessment of bacterial pathogens in fresh rainwater and airborne particulate matter using Real-Time PCR

    NASA Astrophysics Data System (ADS)

    Kaushik, Rajni; Balasubramanian, Rajasekhar

    2012-01-01

    Bacterial pathogens in airborne particulate matter (PM) and in rainwater (RW) were detected using a robust and sensitive Real-Time PCR method. Both RW and PM were collected simultaneously in the tropical atmosphere of Singapore, which were then subjected to analysis for the presence of selected bacterial pathogens and potential pathogen of health concern ( Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Aeromonas hydrophila). These pathogens were found to be prevalent in both PM and RW samples with E. coli being the most prevalent potential pathogen in both types of samples. The temporal distribution of these pathogens in PM and RW was found to be similar to each other. Using the proposed microbiological technique, the atmospheric deposition (dry and wet deposition) of bacterial pathogens to lakes and reservoirs can be studied in view of growing concerns about the outbreak of waterborne diseases.

  2. USGS/EPA collection protocol for bacterial pathogens in soil

    USGS Publications Warehouse

    Griffin, Dale W.; Shaefer, F.L.; Charlena Bowling,; Dino Mattorano,; Tonya Nichols,; Erin Silvestri,

    2014-01-01

    This Sample Collection Procedure (SCP) describes the activities and considerations for the collection of bacterial pathogens from representative surface soil samples (0-5 cm). This sampling depth can be reached without the use of a drill rig, direct-push technology, or other mechanized equipment. This procedure can be used in most soil types but is limited to sampling at or near the ground surface. This protocol has components for two different types of sampling applications: (1) typical sampling, when there is no suspicion of contamination (e.g., surveillance or background studies); and (2) in response to known or suspected accidental contamination (e.g., the presence of animal carcasses). This protocol does not cover sampling in response to a suspected bioterrorist or intentional release event. Surface material is removed to the required depth (0-5 cm) and clean trowel or 50 ml sample tube is used to collect the sample. Sample containers are sealed, bagged, and shipped to the laboratory for analysis. Associated documentation, including a Field Data Log and Chain-of-Custody are also included in this document.

  3. Bacterial biofilm formation, pathogenicity, diagnostics and control: An overview.

    PubMed

    Sawhney, Rajesh; Berry, Vandana

    2009-07-01

    Bacterial biofilms are complex, mono- or poly-microbialn communities adhering to biotic or abiotic surfaces. This adaptation has been implicated as a survival strategy. The formation of biofilms is mediated by mechanical, biochemical and genetical factors. The biofilms enhance the virulence of the pathogen and have their potential role in various infections, such as dental caries, cystic fibrosis, osteonecrosis, urinary tract infection and eye infections. A number of diagnostic techniques, viz., bright-field microscopy, epifluorescence microscopy, scanning electron microscopy, confocal laser scanning microscopy and amplicon length heterogeneity polymerase chain reaction, have been employed for detection of these communities. Researchers have worked on applications of catheter lock solutions, a fish protein coating, acid shock treatment, susceptibility to bacteriophages, etc., for biofilm control. However, we need to rearrange our strategies to have thorough insight and concentrate on priority basis to develop new accurate, precise and rapid diagnostic protocols for detection and evaluation of biofilm. Above all, the strict compliance to these techniques is required for accurate diagnosis and control.

  4. The Capricious Nature of Bacterial Pathogens: Phasevarions and Vaccine Development

    PubMed Central

    Tan, Aimee; Atack, John M.; Jennings, Michael P.; Seib, Kate L.

    2016-01-01

    Infectious diseases are a leading cause of morbidity and mortality worldwide, and vaccines are one of the most successful and cost-effective tools for disease prevention. One of the key considerations for rational vaccine development is the selection of appropriate antigens. Antigens must induce a protective immune response, and this response should be directed to stably expressed antigens so the target microbe can always be recognized by the immune system. Antigens with variable expression, due to environmental signals or phase variation (i.e., high frequency, random switching of expression), are not ideal vaccine candidates because variable expression could lead to immune evasion. Phase variation is often mediated by the presence of highly mutagenic simple tandem DNA repeats, and genes containing such sequences can be easily identified, and their use as vaccine antigens reconsidered. Recent research has identified phase variably expressed DNA methyltransferases that act as global epigenetic regulators. These phase-variable regulons, known as phasevarions, are associated with altered virulence phenotypes and/or expression of vaccine candidates. As such, genes encoding candidate vaccine antigens that have no obvious mechanism of phase variation may be subject to indirect, epigenetic control as part of a phasevarion. Bioinformatic and experimental studies are required to elucidate the distribution and mechanism of action of these DNA methyltransferases, and most importantly, whether they mediate epigenetic regulation of potential and current vaccine candidates. This process is essential to define the stably expressed antigen target profile of bacterial pathogens and thereby facilitate efficient, rational selection of vaccine antigens. PMID:28018352

  5. Selected Bacterial Strains Protect Artemia spp. from the Pathogenic Effects of Vibrio proteolyticus CW8T2

    PubMed Central

    Verschuere, Laurent; Heang, Hanglamong; Criel, Godelieve; Sorgeloos, Patrick; Verstraete, Willy

    2000-01-01

    In this study Vibrio proteolyticus CW8T2 has been identified as a virulent pathogen for Artemia spp. Its infection route has been visualized with transmission electron microscopy. The pathogen affected microvilli and gut epithelial cells, disrupted epithelial cell junctions, and reached the body cavity, where it devastated cells and tissues. In vivo antagonism tests showed that preemptive colonization of the culture water with nine selected bacterial strains protected Artemia juveniles against the pathogenic effects. Two categories of the selected strains could be distinguished: (i) strains providing total protection, as no mortality occurred 2 days after the experimental infection with V. proteolyticus CW8T2, with strain LVS8 as a representative, and (ii) strains providing partial protection, as significant but not total mortality was observed, with strain LVS2 as a representative. The growth of V. proteolyticus CW8T2 in the culture medium was slowed down in the presence of strains LVS2 and LVS8, but growth suppression was distinctly higher with LVS8 than with LVS2. It was striking that the strains that gave only partial protection against the pathogen in the in vivo antagonism test showed also a restricted capability to colonize the Artemia compared to the strains providing total protection. The in vivo antagonism tests and the filtrate experiments showed that probably no extracellular bacterial compounds were involved in the protective action but that the living cells were required to protect Artemia against V. proteolyticus CW8T2. PMID:10698783

  6. Selected bacterial strains protect Artemia spp. from the pathogenic effects of Vibrio proteolyticus CW8T2.

    PubMed

    Verschuere, L; Heang, H; Criel, G; Sorgeloos, P; Verstraete, W

    2000-03-01

    In this study Vibrio proteolyticus CW8T2 has been identified as a virulent pathogen for Artemia spp. Its infection route has been visualized with transmission electron microscopy. The pathogen affected microvilli and gut epithelial cells, disrupted epithelial cell junctions, and reached the body cavity, where it devastated cells and tissues. In vivo antagonism tests showed that preemptive colonization of the culture water with nine selected bacterial strains protected Artemia juveniles against the pathogenic effects. Two categories of the selected strains could be distinguished: (i) strains providing total protection, as no mortality occurred 2 days after the experimental infection with V. proteolyticus CW8T2, with strain LVS8 as a representative, and (ii) strains providing partial protection, as significant but not total mortality was observed, with strain LVS2 as a representative. The growth of V. proteolyticus CW8T2 in the culture medium was slowed down in the presence of strains LVS2 and LVS8, but growth suppression was distinctly higher with LVS8 than with LVS2. It was striking that the strains that gave only partial protection against the pathogen in the in vivo antagonism test showed also a restricted capability to colonize the Artemia compared to the strains providing total protection. The in vivo antagonism tests and the filtrate experiments showed that probably no extracellular bacterial compounds were involved in the protective action but that the living cells were required to protect Artemia against V. proteolyticus CW8T2.

  7. Pattern formation in a growing bacterial colony facilitated by extra-cellular polymeric substances

    NASA Astrophysics Data System (ADS)

    Ghosh, Pushpita; Mondal, Jagannath; Ben-Jacob, Eshel; Levine, Herbert

    2015-03-01

    Self-organization in bacterial colony is quite pervasive and diverse phenomena. Bacteria are known to self-organize into multicellular communities, commonly known as biofilms, in which microbial cells live in close association with a solid surface and are embedded in a self-produced extracellular polymeric substances(EPS). In such dense systems mechanical interactions among the structural components can be expected to significantly contribute to the morphological properties. By a simple particle-based simulation model of nonmotile rod-shaped bacterial cells and EPS secreted in a growing colony, we investigate how the combined mechanical effects can give rise naturally spatial heterogeneity observed in a biofilm. In our individual-based simulation model all the components interact mechanically via repulsive forces by pushing each other away as bacterial cells grow and divide consuming diffusing nutrient and produce EPS. We show that mechanical interactions control the collective behavior of the system, particularly, we show that the presence of non-adsorbing EPS leads spontaneous aggregation of bacterial cells by depletion attraction and generates phase separated patterns in a nonequilibrium growing colony.

  8. Risk assessment of opportunistic bacterial pathogens in drinking water.

    PubMed

    Rusin, P A; Rose, J B; Haas, C N; Gerba, C P

    1997-01-01

    dose for an opportunistic pathogen is lower for immunocompromised subjects or those on antibiotic treatment. These bacteria have been found in drinking water at the following frequencies: P. aeruginosa, < 1%-24%; Acinetobacter, 5%-38%; X. maltophilia, < 1%-2%; Aeromonas, 1%-27%; Moraxella, 10%-80%; M. avium, < 1%-50%; and L. pneumophila, 3%-33%. These data suggest that drinking water could be a source of infection for some of these bacteria. The risk characterization showed that risks of infection from oral ingestion ranged from a low of 7.3 x 10(-9) (7.3/billion) for low exposures to Aeromonas to higher risks predicted at high levels of exposure to Pseudomonas of 9 x 10(-2) (98/100). This higher risk was only predicted for individuals on antibiotics. Overall, the evidence suggests that specific members of HPC bacteria found in drinking water may be causative agents of both hospital- and community-acquired infections. However, the case numbers may be very low and the risks represent levels generally less than 1/10,000 for a single exposure to the bacterial agent. Future research needs include (1) determining the seasonal concentrations of these bacteria in drinking water, (2) conducting adequate dose-response studies in animal subjects or human volunteers, (3) determining the health risks for an individual with multiple exposures to the opportunistic pathogens, and (4) evaluating the increase in host susceptibility conferred by antibiotic use or immunosuppression.

  9. Molecular and Structural Discrimination of Proline Racemase and Hydroxyproline-2-Epimerase from Nosocomial and Bacterial Pathogens

    PubMed Central

    Goytia, Maira; Chamond, Nathalie; Cosson, Alain; Coatnoan, Nicolas; Hermant, Daniel; Berneman, Armand; Minoprio, Paola

    2007-01-01

    The first eukaryotic proline racemase (PRAC), isolated from the human Trypanosoma cruzi pathogen, is a validated therapeutic target against Chagas' disease. This essential enzyme is implicated in parasite life cycle and infectivity and its ability to trigger host B-cell nonspecific hypergammaglobulinemia contributes to parasite evasion and persistence. Using previously identified PRAC signatures and data mining we present the identification and characterization of a novel PRAC and five hydroxyproline epimerases (HyPRE) from pathogenic bacteria. Single-mutation of key HyPRE catalytic cysteine abrogates enzymatic activity supporting the presence of two reaction centers per homodimer. Furthermore, evidences are provided that Brucella abortus PrpA [for ‘proline racemase’ virulence factor A] and homologous proteins from two Brucella spp are bona fide HyPREs and not ‘one way’ directional PRACs as described elsewhere. Although the mechanisms of aminoacid racemization and epimerization are conserved between PRAC and HyPRE, our studies demonstrate that substrate accessibility and specificity partly rely on contraints imposed by aromatic or aliphatic residues distinctively belonging to the catalytic pockets. Analysis of PRAC and HyPRE sequences along with reaction center structural data disclose additional valuable elements for in silico discrimination of the enzymes. Furthermore, similarly to PRAC, the lymphocyte mitogenicity displayed by HyPREs is discussed in the context of bacterial metabolism and pathogenesis. Considering tissue specificity and tropism of infectious pathogens, it would not be surprising if upon infection PRAC and HyPRE play important roles in the regulation of the intracellular and extracellular amino acid pool profiting the microrganism with precursors and enzymatic pathways of the host. PMID:17849014

  10. Pathogenicity testing of shellfish hatchery bacterial isolates on Pacific oyster Crassostrea gigas larvae.

    PubMed

    Estes, Robyn M; Friedman, Carolyn S; Elston, Ralph A; Herwig, Russell P

    2004-03-10

    Bacterial diseases are a major cause of larval mortality in shellfish hatcheries. Even with proper sanitation measures, bacterial pathogens cannot be eliminated in all cases. The pathogenicity of bacteria isolated from Pacific Northwest shellfish hatcheries to Pacific oyster Crassostrea gigas larvae was investigated. We found 3 highly pathogenic strains and 1 mildly pathogenic strain among 33 isolates tested. These strains appear to be members of the genus Vibrio. Although there have been many studies of bivalve bacterial pathogens, a standard method to assess bacterial pathogenicity in bivalve larvae is needed. Thus, we developed 2 methods using either 15 ml conical tubes or tissue culture plates that were employed for rapidly screening bacterial strains for pathogenicity to Pacific oyster larvae. The tissue culture plates worked well for screening both mildly pathogenic strains and LD50 (lethal dose) assays. This method allowed for non-intrusive and non-destructive observation of the oyster larvae with a dissecting microscope. The LD50 for the 3 highly pathogenic strains ranged between 1.6 and 3.6 x 10(4) colony forming units (CFU) ml(-1) after 24 h and between 3.2 x 102 and 1.9 x 10(3) CFU ml(-1) after 48 h.

  11. Parasites can enhance infections of fish with bacterial pathogens

    USDA-ARS?s Scientific Manuscript database

    In aquaculture systems, fish are commonly infected by multiple pathogens, including parasites. Parasite Ichthyophthirius multifiliis (Ich) and bacterium Edwardsiella ictaluri are two common pathogens of cultured channel catfish. The objectives were to 1) evaluate the susceptibility of Ich parasitize...

  12. The bacterial microbiome of dermacentor andersoni ticks influences pathogen susceptibility

    USDA-ARS?s Scientific Manuscript database

    Ticks are of medical and veterinary importance due to their ability to transmit pathogens to humans and animals. The Rocky Mountain wood tick, Dermacentor andersoni, is a vector of a number of pathogens, including Anaplasma marginale, which is the most widespread tick-borne pathogen of livestock. Al...

  13. High Temperature and Bacteriophages Can Indirectly Select for Bacterial Pathogenicity in Environmental Reservoirs

    PubMed Central

    Friman, Ville-Petri; Hiltunen, Teppo; Jalasvuori, Matti; Lindstedt, Carita; Laanto, Elina; Örmälä, Anni-Maria; Laakso, Jouni; Mappes, Johanna; Bamford, Jaana K. H.

    2011-01-01

    The coincidental evolution hypothesis predicts that traits connected to bacterial pathogenicity could be indirectly selected outside the host as a correlated response to abiotic environmental conditions or different biotic species interactions. To investigate this, an opportunistic bacterial pathogen, Serratia marcescens, was cultured in the absence and presence of the lytic bacteriophage PPV (Podoviridae) at 25°C and 37°C for four weeks (N = 5). At the end, we measured changes in bacterial phage-resistance and potential virulence traits, and determined the pathogenicity of all bacterial selection lines in the Parasemia plantaginis insect model in vivo. Selection at 37°C increased bacterial motility and pathogenicity but only in the absence of phages. Exposure to phages increased the phage-resistance of bacteria, and this was costly in terms of decreased maximum population size in the absence of phages. However, this small-magnitude growth cost was not greater with bacteria that had evolved in high temperature regime, and no trade-off was found between phage-resistance and growth rate. As a result, phages constrained the evolution of a temperature-mediated increase in bacterial pathogenicity presumably by preferably infecting the highly motile and virulent bacteria. In more general perspective, our results suggest that the traits connected to bacterial pathogenicity could be indirectly selected as a correlated response by abiotic and biotic factors in environmental reservoirs. PMID:21423610

  14. Phage-host interplay: examples from tailed phages and Gram-negative bacterial pathogens.

    PubMed

    Chaturongakul, Soraya; Ounjai, Puey

    2014-01-01

    Complex interactions between bacteriophages and their bacterial hosts play significant roles in shaping the structure of environmental microbial communities, not only by genetic transduction but also by modification of bacterial gene expression patterns. Survival of phages solely depends on their ability to infect their bacterial hosts, most importantly during phage entry. Successful dynamic adaptation of bacteriophages when facing selective pressures, such as host adaptation and resistance, dictates their abundance and diversification. Co-evolution of the phage tail fibers and bacterial receptors determine bacterial host ranges, mechanisms of phage entry, and other infection parameters. This review summarizes the current knowledge about the physical interactions between tailed bacteriophages and bacterial pathogens (e.g., Salmonella enterica and Pseudomonas aeruginosa) and the influences of the phage on host gene expression. Understanding these interactions can offer insights into phage-host dynamics and suggest novel strategies for the design of bacterial pathogen biological controls.

  15. Vibrio cholerae hemagglutinin(HA)/protease: an extracellular metalloprotease with multiple pathogenic activities

    PubMed Central

    Benitez, Jorge A.; Silva, Anisia J.

    2016-01-01

    Vibrio cholerae of serogroup O1 and O139, the etiological agent of the diarrheal disease cholera, expresses the extracellular Zn-dependent metalloprotease hemagglutinin (HA)/protease also reported as vibriolysin. This enzyme is also produced by non-O1/O139 (non-cholera) strains that cause mild, sporadic illness (i.e. gastroenteritis, wound or ear infections). Orthologs of HA/protease are present in other members of the Vibrionaceae family pathogenic to humans and fish. HA/protease belongs to the M4 neutral peptidase family and displays significant amino acid sequence homology to Pseudomonas aeruginosa elastase (LasB) and Bacillus thermoproteolyticus thermolysin. It exhibits a broad range of potentially pathogenic activities in cell culture and animal models. These activities range from the covalent modification of other toxins, the degradation of the protective mucus barrier and disruption of intestinal tight junctions. Here we review (i) the structure and regulation of HA/protease expression, (ii) its interaction with other toxins and the intestinal mucosa and (iii) discuss the possible role(s) of HA/protease in the pathogenesis of cholera. PMID:26952544

  16. Structural and functional studies of multiheme cytochromes C involved in extracellular electron transport in bacterial dissimilatory metal reduction.

    PubMed

    Tikhonova, T V; Popov, V O

    2014-12-01

    Bacteria utilizing insoluble mineral forms of metal oxides as electron acceptors in respiratory processes are widespread in the nature. The electron transfer from a pool of reduced quinones in the cytoplasmic membrane across the periplasm to the bacterial outer membrane and then to an extracellular acceptor is a key step in bacterial dissimilatory metal reduction. Multiheme cytochromes c play a crucial role in the extracellular electron transfer. The bacterium Shewanella oneidensis MR-1 was used as a model organism to study the mechanism of extracellular electron transport. In this review, we discuss recent data on the composition, structures, and functions of multiheme cytochromes c and their functional complexes responsible for extracellular electron transport in Shewanella oneidensis.

  17. Binding of Hg by bacterial extracellular polysaccharide: a possible role in Hg tolerance.

    PubMed

    Cruz, Kimberly; Guézennec, Jean; Barkay, Tamar

    2017-04-10

    Bacteria employ adaptive mechanisms of mercury (Hg) tolerance to survive in environments containing elevated Hg concentrations. The potential of extracellular polysaccharides (EPS) production by bacteria as a mechanism of Hg tolerance has not been previously investigated. The objectives of this study were to determine if bacterial EPS sorb Hg, and if so does sorption provide protection against Hg toxicity. Purified EPS with different chemical compositions produced by bacterial isolates from microbial mats in French Polynesian atolls and deep-sea hydrothermal vents were assessed for Hg sorption. The data showed that EPS sorbed up to 82% of Hg from solution, that this sorption was dependent on EPS composition, and that sorption was a saturable mechanism. Hg uptake capacities ranged from 0.005 to 0.454 mmol Hg/g for the different EPS. To determine if EPS production could alter bacterial Hg tolerance, Escherichia coli K-12 strains and their EPS defective mutants were tested by the disc inhibition assay. Mercury inhibited growth in a dose-dependent manner with wild-type strains having smaller (~1 mm), but statistically significant, zones of inhibition than various mutants and this difference was related to a 2-fold decline in the amount of EPS produced by the mutants relative to cell biomass. These experiments identified colanic acid and hexosamine as Hg-binding moieties in EPS. Together these data indicate that binding of Hg to EPS affords a low level of resistance to the producing bacteria.

  18. Molecular detection of bacterial pathogens using microparticle enhanced double-stranded DNA probes.

    PubMed

    Riahi, Reza; Mach, Kathleen E; Mohan, Ruchika; Liao, Joseph C; Wong, Pak Kin

    2011-08-15

    Rapid, specific, and sensitive detection of bacterial pathogens is essential toward clinical management of infectious diseases. Traditional approaches for pathogen detection, however, often require time-intensive bacterial culture and amplification procedures. Herein, a microparticle enhanced double-stranded DNA probe is demonstrated for rapid species-specific detection of bacterial 16S rRNA. In this molecular assay, the binding of the target sequence to the fluorophore conjugated probe thermodynamically displaces the quencher probe and allows the fluorophore to fluoresce. By incorporation of streptavidin-coated microparticles to localize the biotinylated probes, the sensitivity of the assay can be improved by 3 orders of magnitude. The limit of detection of the assay is as few as eight bacteria without target amplification and is highly specific against other common pathogens. Its applicability toward clinical diagnostics is demonstrated by directly identifying bacterial pathogens in urine samples from patients with urinary tract infections.

  19. Secreted and immunogenic proteins produced by the honeybee bacterial pathogen, Paenibacillus larvae.

    PubMed

    Antúnez, Karina; Anido, Matilde; Evans, Jay D; Zunino, Pablo

    2010-03-24

    American Foulbrood is a severe disease affecting larvae of honeybee Apis mellifera, causing significant decrease in the honeybee population, beekeeping industries and agricultural production. In spite of its importance, little is known about the virulence factors secreted by Paenibacillus larvae during larval infection. The aim of the present work was to perform a first approach to the identification and characterization of P. larvae secretome. P. larvae secreted proteins were analyzed by SDS-PAGE and identified by MALDI-TOF. Protein toxicity was evaluated using an experimental model based on feeding of A. mellifera larvae and immunogenicity was evaluated by Western blot, using an antiserum raised against cells and spores of P. larvae. Ten different proteins were identified among P. larvae secreted proteins, including proteins involved in transcription, metabolism, translation, cell envelope, transport, protein folding, degradation of polysaccharides and motility. Although most of these proteins are cytosolic, many of them have been previously detected in the extracellular medium of different Bacillus spp. cultures and have been related to virulence. The secreted proteins resulted highly toxic and immunogenic when larvae were exposed using an experimental model. This is the first description of proteins secreted by the honeybee pathogen P. larvae. This information may be relevant for the elucidation of bacterial pathogenesis mechanisms. Copyright 2009 Elsevier B.V. All rights reserved.

  20. Detecting human bacterial pathogens in wastewater treatment plants by a high-throughput shotgun sequencing technique.

    PubMed

    Cai, Lin; Zhang, Tong

    2013-05-21

    Human pathogens are one of the major threats to global public health. Wastewater treatment plants (WWTPs) serve as city guts to receive and digest various human pathogens. Several techniques have been developed to detect human pathogens in WWTPs and to assess potential environmental risks. In this study, we employed 24 metagenomic DNA data sets derived from a high-throughput shotgun sequencing technique to more accurately and efficiently detect human bacterial pathogens in influent, activated sludge, and effluent of two Hong Kong WWTPs. Each data set was quality-filtered and normalized to 12,500,000 DNA sequences with a length of 150-190 bp. Then, a BLASTN search against Greengenes general 16S rRNA gene database and human pathogenic bacteria 16S rRNA gene database, a BLASTX search against human pathogenic bacteria virulence factor database, as well as MetaPhlAn analysis were conducted to survey the distribution, diversity, and abundance of human bacterial pathogens. The results revealed that (i) nine bacterial pathogens were detected; (ii) the overall pathogenic bacteria abundance was estimated as 0.06-3.20% in the total bacteria population using 16S rRNA gene fingerprinting; (iii) pathogenic bacteria detected in activated sludge and effluent shared similar profiles but were different from influent based on both 16S rRNA gene and virulence factor fingerprintings; (iv) Mycobacterium tuberculosis -like species may present potential pathogenic risks because it was detected with high abundance in both activated sludge and effluent. These findings provided a comprehensive profile of commonly concerned human pathogens in two Hong Kong WWTPs and demonstrated that the high-throughput shotgun sequencing technique is a feasible and effectual approach for environmental detection of human bacterial pathogens.

  1. Preparation of Antioxidant Peptides from Salmon Byproducts with Bacterial Extracellular Proteases

    PubMed Central

    Wu, Ribang; Chen, Leilei; Liu, Dan; Huang, Jiafeng; Zhang, Jiang; Xiao, Xiao; Lei, Ming; Chen, Yuelin; He, Hailun

    2017-01-01

    Bacterial extracellular proteases from six strains of marine bacteria and seven strains of terrestrial bacteria were prepared through fermentation. Proteases were analyzed through substrate immersing zymography and used to hydrolyze the collagen and muscle proteins from a salmon skin byproduct, respectively. Collagen could be degraded much more easily than muscle protein, but it commonly showed weaker antioxidant capability. The hydrolysate of muscle proteins was prepared with crude enzymes from Pseudoalteromonas sp. SQN1 displayed the strongest activity of antioxidant in DPPH and hydroxyl radical scavenging assays (74.06% ± 1.14% and 69.71% ± 1.97%), but did not perform well in Fe2+ chelating assay. The antioxidant fractions were purified through ultrafiltration, cation exchange chromatography, and size exclusion chromatography gradually, and the final purified fraction U2-S2-I displayed strong activity of antioxidant in DPPH, hydroxyl radical scavenging assays (IC50 = 0.263 ± 0.018 mg/mL and 0.512 ± 0.055 mg/mL), and oxygen radical absorption capability assay (1.960 ± 0.381 mmol·TE/g). The final purified fraction U2-S2-I possessed the capability to protect plasmid DNA against the damage of hydroxyl radical and its effect was similar to that of the original hydrolysis product. It indicated that U2-S2-I might be the major active fraction of the hydrolysate. This study proved that bacterial extracellular proteases could be utilized in hydrolysis of a salmon byproduct. Compared with collagen, muscle proteins was an ideal material used as an enzymatic substrate to prepare antioxidant peptides. PMID:28085023

  2. Biogenic polyamines capture CO2 and accelerate extracellular bacterial CaCO3 formation.

    PubMed

    Yasumoto, Ko; Yasumoto-Hirose, Mina; Yasumoto, Jun; Murata, Ryo; Sato, Shun-Ichi; Baba, Megumi; Mori-Yasumoto, Kanami; Jimbo, Mitsuru; Oshima, Yasukatsu; Kusumi, Takenori; Watabe, Shugo

    2014-08-01

    Bacteria, including cyanobacteria, as well as some fungi, are known to deposit calcium carbonate (CaCO(3)) extracellularly in calcium-containing artificial medium. Despite extensive investigation, the mechanisms involved in extracellular formation of CaCO(3) by bacteria have remained unclear. The ability of synthetic amines to remove carbon dioxide (CO(2)) from natural gas led us to examine the role of biogenic polyamines in CaCO(3) deposition by bacteria. Here, we demonstrated that biogenic polyamines such as putrescine, spermidine, and spermine were able to react with atmospheric CO(2) and the resultant carbamate anion was characterized by using nuclear magnetic resonance (NMR) analysis. Biogenic polyamines accelerated the formation of CaCO(3), and we artificially synthesized the dumbbell-shaped calcites, which had the same form as observed with bacterial CaCO3 precipitates, under nonbacterial conditions by using polyamines. The reaction rate of calcification increased with temperature with an optimum of around 40 °C. Our observation suggests a novel scheme for CO(2) dissipation that could be a potential tool in reducing atmospheric CO(2) levels and, therefore, global warming.

  3. Gene Expression in Gut Symbiotic Organ of Stinkbug Affected by Extracellular Bacterial Symbiont

    PubMed Central

    Futahashi, Ryo; Tanaka, Kohjiro; Tanahashi, Masahiko; Nikoh, Naruo; Kikuchi, Yoshitomo; Lee, Bok Luel; Fukatsu, Takema

    2013-01-01

    The bean bug Riptortus pedestris possesses a specialized symbiotic organ in a posterior region of the midgut, where numerous crypts harbor extracellular betaproteobacterial symbionts of the genus Burkholderia. Second instar nymphs orally acquire the symbiont from the environment, and the symbiont infection benefits the host by facilitating growth and by occasionally conferring insecticide resistance. Here we performed comparative transcriptomic analyses of insect genes expressed in symbiotic and non-symbiotic regions of the midgut dissected from Burkholderia-infected and uninfected R. pedestris. Expression sequence tag analysis of cDNA libraries and quantitative reverse transcription PCR identified a number of insect genes expressed in symbiosis- or aposymbiosis-associated patterns. For example, genes up-regulated in symbiotic relative to aposymbiotic individuals, including many cysteine-rich secreted protein genes and many cathepsin protease genes, are likely to play a role in regulating the symbiosis. Conversely, genes up-regulated in aposymbiotic relative to symbiotic individuals, including a chicken-type lysozyme gene and a defensin-like protein gene, are possibly involved in regulation of non-symbiotic bacterial infections. Our study presents the first transcriptomic data on gut symbiotic organ of a stinkbug, which provides initial clues to understanding of molecular mechanisms underlying the insect-bacterium gut symbiosis and sheds light on several intriguing commonalities between endocellular and extracellular symbiotic associations. PMID:23691247

  4. A refined technique for extraction of extracellular matrices from bacterial biofilms and its applicability

    PubMed Central

    Chiba, Akio; Sugimoto, Shinya; Sato, Fumiya; Hori, Seiji; Mizunoe, Yoshimitsu

    2015-01-01

    Biofilm-forming bacteria embedded in polymeric extracellular matrices (ECMs) that consist of polysaccharides, proteins and/or extracellular DNAs (eDNAs) acquire high resistance to antimicrobial agents and host immune systems. To understand molecular mechanisms of biofilm formation and maintenance and to develop therapeutic countermeasures against chronic biofilm-associated infections, reliable methods to isolate ECMs are inevitable. In this study, we refined the ECM extraction method recently reported and evaluated its applicability. Using three Staphylococcus aureus biofilms in which proteins, polysaccharides or eDNAs are major contributors to their integrity, ECMs were extracted using salts and detergents. We found that extraction with 1.5 M sodium chloride (NaCl) could be optimum for not only ECM proteins but also polysaccharides and eDNAs. In addition, long-time incubation was not necessary for efficient ECM isolation. Lithium chloride (LiCl) was comparative to NaCl but is more expensive. In contrast to SDS, NaCl hardly caused leakage of intracellular proteins and did not affect viability of bacterial cells within biofilms. Furthermore, this method is applicable to other bacteria such as Gram-positive Staphylococcus epidermidis and Gram-negative Escherichia coli and Pseudomonas aeruginosa. Thus, this refined method is very simple, rapid, low cost and non-invasive and could be used for a broad range of applications. PMID:25154775

  5. A refined technique for extraction of extracellular matrices from bacterial biofilms and its applicability.

    PubMed

    Chiba, Akio; Sugimoto, Shinya; Sato, Fumiya; Hori, Seiji; Mizunoe, Yoshimitsu

    2015-05-01

    Biofilm-forming bacteria embedded in polymeric extracellular matrices (ECMs) that consist of polysaccharides, proteins and/or extracellular DNAs (eDNAs) acquire high resistance to antimicrobial agents and host immune systems. To understand molecular mechanisms of biofilm formation and maintenance and to develop therapeutic countermeasures against chronic biofilm-associated infections, reliable methods to isolate ECMs are inevitable. In this study, we refined the ECM extraction method recently reported and evaluated its applicability. Using three Staphylococcus aureus biofilms in which proteins, polysaccharides or eDNAs are major contributors to their integrity, ECMs were extracted using salts and detergents. We found that extraction with 1.5 M sodium chloride (NaCl) could be optimum for not only ECM proteins but also polysaccharides and eDNAs. In addition, long-time incubation was not necessary for efficient ECM isolation. Lithium chloride (LiCl) was comparative to NaCl but is more expensive. In contrast to SDS, NaCl hardly caused leakage of intracellular proteins and did not affect viability of bacterial cells within biofilms. Furthermore, this method is applicable to other bacteria such as Gram-positive Staphylococcus epidermidis and Gram-negative Escherichia coli and Pseudomonas aeruginosa. Thus, this refined method is very simple, rapid, low cost and non-invasive and could be used for a broad range of applications.

  6. High-throughput sequencing for the study of bacterial pathogen biology

    PubMed Central

    McAdam, Paul R; Richardson, Emily J; Fitzgerald, J Ross

    2014-01-01

    A revolution in sequencing technologies in recent years has led to dramatically increased throughput and reduced cost of bacterial genome sequencing. An increasing number of applications of the new technologies are providing broad insights into bacterial evolution, epidemiology, and pathogenesis. For example, the capacity to sequence large numbers of bacterial isolates is enabling high resolution phylogenetic analyses of bacterial populations leading to greatly enhanced understanding of the emergence, adaptation, and transmission of pathogenic clones. In addition, RNA-seq offers improved quantification and resolution for transcriptomic analysis, and the combination of high-throughput sequencing with transposon mutagenesis is a powerful approach for the identification of bacterial determinants required for survival in vivo. In this concise review we provide selected examples of how high throughput sequencing is being applied to understand the biology of bacterial pathogens, and discuss future technological advances likely to have a profound impact on the field. PMID:25033019

  7. The disease complex of the gypsy moth. II. Aerobic bacterial pathogens

    Treesearch

    J.D. Podgwaite; R.W. Campbell

    1972-01-01

    Eighty-six pathogenic aerobic bacterial isolates from diseased gypsy moth larvae collected in both sparse and dense populations were characterized and identified as members of the families Bacillaceae, Enterobacteriaceae, Lactobacillaceae, Pseudomonadaceae, and Achromobacteraceae. The commonest pathogens were Streptococcus faecalis, Bacillus cereus, Bacillus...

  8. Effectiveness of Polyvalent Bacterial Lysate and Autovaccines Against Upper Respiratory Tract Bacterial Colonization by Potential Pathogens: A Randomized Study

    PubMed Central

    Zagólski, Olaf; Stręk, Paweł; Kasprowicz, Andrzej; Białecka, Anna

    2015-01-01

    Background Polyvalent bacterial lysate (PBL) is an oral immunostimulating vaccine consisting of bacterial standardized lysates obtained by lysis of different strains of bacteria. Autovaccines are individually prepared based on the results of smears obtained from the patient. Both types of vaccine can be used to treat an ongoing chronic infection. This study sought to determine which method is more effective against nasal colonization by potential respiratory tract pathogens. Material/Methods We enrolled 150 patients with aerobic Gram stain culture and count results indicating bacterial colonization of the nose and/or throat by potential pathogens. The participants were randomly assigned to each of the following groups: 1. administration of PBL, 2. administration of autovaccine, and 3. no intervention (controls). Results Reduction of the bacterial count in Streptococcus pneumoniae-colonized participants was significant after the autovaccine (p<0.001) and PBL (p<0.01). Reduction of the bacterial count of other β-hemolytic streptococcal strains after treatment with the autovaccine was significant (p<0.01) and was non-significant after PBL. In Haemophilus influenzae colonization, significant reduction in the bacterial count was noted in the PBL group (p<0.01). Methicillin-resistant Staphylococcus aureus colonization did not respond to either treatment. Conclusions The autovaccine is more effective than PBL for reducing bacterial count of Streptococcus pneumoniae and β-hemolytic streptococci, while PBL was more effective against Haemophilus influenzae colonization. PMID:26434686

  9. Reduced Set of Virulence Genes Allows High Accuracy Prediction of Bacterial Pathogenicity in Humans

    PubMed Central

    Iraola, Gregorio; Vazquez, Gustavo; Spangenberg, Lucía; Naya, Hugo

    2012-01-01

    Although there have been great advances in understanding bacterial pathogenesis, there is still a lack of integrative information about what makes a bacterium a human pathogen. The advent of high-throughput sequencing technologies has dramatically increased the amount of completed bacterial genomes, for both known human pathogenic and non-pathogenic strains; this information is now available to investigate genetic features that determine pathogenic phenotypes in bacteria. In this work we determined presence/absence patterns of different virulence-related genes among more than finished bacterial genomes from both human pathogenic and non-pathogenic strains, belonging to different taxonomic groups (i.e: Actinobacteria, Gammaproteobacteria, Firmicutes, etc.). An accuracy of 95% using a cross-fold validation scheme with in-fold feature selection is obtained when classifying human pathogens and non-pathogens. A reduced subset of highly informative genes () is presented and applied to an external validation set. The statistical model was implemented in the BacFier v1.0 software (freely available at ), that displays not only the prediction (pathogen/non-pathogen) and an associated probability for pathogenicity, but also the presence/absence vector for the analyzed genes, so it is possible to decipher the subset of virulence genes responsible for the classification on the analyzed genome. Furthermore, we discuss the biological relevance for bacterial pathogenesis of the core set of genes, corresponding to eight functional categories, all with evident and documented association with the phenotypes of interest. Also, we analyze which functional categories of virulence genes were more distinctive for pathogenicity in each taxonomic group, which seems to be a completely new kind of information and could lead to important evolutionary conclusions. PMID:22916122

  10. Rapid CD8+ Function Is Critical for Protection of Neonatal Mice from an Extracellular Bacterial Enteropathogen

    PubMed Central

    Siefker, David T.; Adkins, Becky

    2017-01-01

    Both human and murine neonates are characteristically highly susceptible to bacterial infections. However, we recently discovered that neonatal mice are surprisingly highly resistant to oral infection with Yersinia enterocolitica. This resistance was linked with activation of both innate and adaptive responses, involving innate phagocytes, CD4+ cells, and B cells. We have now extended these studies and found that CD8+ cells also contribute importantly to neonatal protection from Y. enterocolitica. Strikingly, neonatal CD8+ cells in the mesenteric lymph nodes (MLN) are rapidly mobilized, increasing in proportion, number, and IFNγ production as early as 48 h post infection. This early activation appears to be critical for protection since B2m−/− neonates are significantly more susceptible than wt neonates to primary Y. enterocolitica infection. In the absence of CD8+ cells, Y. enterocolitica rapidly disseminated to peripheral tissues. Within 48 h of infection, both the spleens and livers of B2m−/−, but not wt, neonates became heavily colonized, likely leading to their deaths from sepsis. In contrast to primary infection, CD8+ cells were dispensable for the generation of immunological memory protective against secondary infection. These results indicate that CD8+ cells in the neonatal MLN contribute importantly to protection against an extracellular bacterial enteropathogen but, notably, they appear to act during the early innate phase of the immune response. PMID:28119902

  11. Particle-associated extracellular enzyme activity and bacterial community composition across the Canadian Arctic Ocean.

    PubMed

    Kellogg, Colleen T E; Deming, Jody W

    2014-08-01

    Microbial enzymatic hydrolysis of marine-derived particulate organic carbon (POC) can be a dominant mechanism for attenuating carbon flux in cold Arctic waters during spring and summer. Whether this mechanism depends on composition of associated microbial communities and extends into other seasons is not known. Bacterial community composition (BCC) and extracellular enzyme activity (EEA, for leucine aminopeptidases, glucosidases and chitobiases) were measured on small suspended particles and potentially sinking aggregates collected during fall from waters of the biologically productive North Water and river-impacted Beaufort Sea. Although other environmental variables appeared influential, both BCC and EEA varied along a marine productivity gradient in the two regions. Aggregates harbored the most distinctive bacterial communities, with a small number of taxa driving differences between particle-size classes (1.0-60 and > 60 μm) and free-living bacteria (0.2-1.0 μm). Significant relationships between patterns in particle-associated BCC and EEA suggest strong links between these two variables. Calculations indicated that up to 80% of POC in the euphotic zone of the North Water, and 20% in the Beaufort Sea, may be hydrolyzed enzymatically, underscoring the importance of this mechanism in attenuating carbon fluxes in Arctic waters even as winter approaches. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  12. Influence of bacterial extracellular polymeric substances on the formation of carbonaceous and nitrogenous disinfection byproducts.

    PubMed

    Wang, Zhikang; Kim, Junsung; Seo, Youngwoo

    2012-10-16

    Considering the regulatory presence of residual chlorine in water distribution systems, untreated organic matter may not be the sole contributor to disinfection byproduct (DBP) formation, given the presence of microbial biofilm with extracellular polymeric substances (EPS). This study investigated the influence of bacterial EPS on the formation of carbonaceous DBPs (C-DBPs) and nitrogenous DBPs (N-DBPs), reacting chlorine with Pseudomonas strains that produce different quantities and composition of EPS. When biomass is reacted in excess to chlorine, both C-DBPs and N-DBPs were produced without preference for speciation. However, under an excess of chlorine compared to biomass, increased EPS content led to enhanced formation of DBPs. The DBP yield of haloacetic acids (HAAs) was higher than that of trihalomethanes where dichloroacetic acid was dominant in HAA species. Additionally, chemical composition of EPS influenced the yields of DBPs. The N-DBP yield from P. putida EPS was two times higher than that of P. aeruginosa EPS, which suggested that higher organic nitrogen content in EPS contributes to higher N-DBP yield. Moreover, time-based experiments revealed that DBP formation from biomass occurs rapidly, reaching a maximum in less than four hours. Combined results suggest that bacterial EPS have significant roles in both the formation and fate of DBPs.

  13. Louse-borne bacterial pathogens in lice (Phthiraptera) of rodents and cattle from Egypt.

    PubMed

    Reeves, Will K; Szumlas, Daniel E; Moriarity, John R; Loftis, Amanda D; Abbassy, Magda M; Helmy, Ibrahim M; Dasch, Gregory A

    2006-04-01

    We collected 1,023 lice, representing 5 species, from rats and domestic cattle throughout 13 governorates in Egypt and tested these lice for Anaplasma marginale, Bartonella spp., Brucella spp., Borrelia recurrentis, Coxiella burnetii, Francisella tularensis, and Rickettsia spp. by PCR amplification and sequencing. Five different louse-borne bacterial agents were detected in lice from rodents or cattle, including "Bartonella rattimassiliensis", "B. phoceensis", and Bartonella sp. near Bartonella tribocorum, Coxiella burnetii, and Rickettsia typhi. More lice from governorates bordering the Mediterranean and Red Seas contained pathogens. Our data indicate that lice of urban and domestic animals harbor pathogenic or potentially pathogenic bacterial agents throughout Egypt.

  14. [Influence of human gastrointestinal tract bacterial pathogens on host cell apoptosis].

    PubMed

    Wronowska, Weronika; Godlewska, Renata; Jagusztyn-Krynicka, Elzbieta Katarzyna

    2005-01-01

    Several pathogenic bacteria are able to trigger apoptosis in the host cell, but the mechanisms by which it occurs differ, and the resulting pathology can take different courses. Induction and/or blockage of programmed cell death upon infection is a result of complex interaction of bacterial proteins with cellular proteins involved in signal transduction and apoptosis. In this review we focus on pro/anti-apoptotic activities exhibited by two enteric pathogens Salmonella enterica, Yersinia spp. and gastric pathogen Helicobacter pylori. We present current knowledge on how interaction between mammalian and bacterial cell relates to the molecular pathways of apoptosis, and what is the role of apoptosis in pathogenesis.

  15. Pseudomonas fluorescens Filamentous Hemagglutinin, an Iron-Regulated Protein, Is an Important Virulence Factor that Modulates Bacterial Pathogenicity

    PubMed Central

    Sun, Yuan-Yuan; Chi, Heng; Sun, Li

    2016-01-01

    Pseudomonas fluorescens is a common bacterial pathogen to a wide range of aquaculture animals including various species of fish. In this study, we employed proteomic analysis and identified filamentous hemagglutinin (FHA) as an iron-responsive protein secreted by TSS, a pathogenic P. fluorescens isolate. In vitro study showed that compared to the wild type, the fha mutant TSSfha (i) exhibited a largely similar vegetative growth profile but significantly retarded in the ability of biofilm growth and producing extracellular matrix, (ii) displayed no apparent flagella and motility, (iii) was defective in the attachment to host cells and unable to form self-aggregation, (iv) displayed markedly reduced capacity of hemagglutination and surviving in host serum. In vivo infection analysis revealed that TSSfha was significantly attenuated in the ability of dissemination in fish tissues and inducing host mortality, and that antibody blocking of the natural FHA produced by the wild type TSS impaired the infectivity of the pathogen. Furthermore, when introduced into turbot as a subunit vaccine, recombinant FHA elicited a significant protection against lethal TSS challenge. Taken together, these results indicate for the first time that P. fluorescens FHA is a key virulence factor essential to multiple biological processes associated with pathogenicity. PMID:27602029

  16. Pseudomonas fluorescens Filamentous Hemagglutinin, an Iron-Regulated Protein, Is an Important Virulence Factor that Modulates Bacterial Pathogenicity.

    PubMed

    Sun, Yuan-Yuan; Chi, Heng; Sun, Li

    2016-01-01

    Pseudomonas fluorescens is a common bacterial pathogen to a wide range of aquaculture animals including various species of fish. In this study, we employed proteomic analysis and identified filamentous hemagglutinin (FHA) as an iron-responsive protein secreted by TSS, a pathogenic P. fluorescens isolate. In vitro study showed that compared to the wild type, the fha mutant TSSfha (i) exhibited a largely similar vegetative growth profile but significantly retarded in the ability of biofilm growth and producing extracellular matrix, (ii) displayed no apparent flagella and motility, (iii) was defective in the attachment to host cells and unable to form self-aggregation, (iv) displayed markedly reduced capacity of hemagglutination and surviving in host serum. In vivo infection analysis revealed that TSSfha was significantly attenuated in the ability of dissemination in fish tissues and inducing host mortality, and that antibody blocking of the natural FHA produced by the wild type TSS impaired the infectivity of the pathogen. Furthermore, when introduced into turbot as a subunit vaccine, recombinant FHA elicited a significant protection against lethal TSS challenge. Taken together, these results indicate for the first time that P. fluorescens FHA is a key virulence factor essential to multiple biological processes associated with pathogenicity.

  17. Fluorescence spectroscopy for rapid detection and classification of bacterial pathogens

    USDA-ARS?s Scientific Manuscript database

    This study deals with the rapid detection and classification of three bacteria, Escherichia coli, Salmonella, and Campylobacter, using fluorescence spectroscopy and multivariative analysis. Each bacterial sample was diluted in physiologic saline for analysis. Fluoroscence spectra were collected ...

  18. Rapid detection of bacterial pathogens using flourescence spectroscopy and chemometrics

    USDA-ARS?s Scientific Manuscript database

    This work presents the development of a method for rapid bacterial identification based on the fluorescence spectroscopy combined with multivariate analysis. Fluorescence spectra of pure three different genera of bacteria (Escherichia coli, Salmonella, and Campylobacter) were collected from 200...

  19. Greater Species Richness of Bacterial Skin Symbionts Better Suppresses the Amphibian Fungal Pathogen Batrachochytrium Dendrobatidis.

    PubMed

    Piovia-Scott, Jonah; Rejmanek, Daniel; Woodhams, Douglas C; Worth, S Joy; Kenny, Heather; McKenzie, Valerie; Lawler, Sharon P; Foley, Janet E

    2017-07-01

    The symbiotic microbes that grow in and on many organisms can play important roles in protecting their hosts from pathogen infection. While species diversity has been shown to influence community function in many other natural systems, the question of how species diversity of host-associated symbiotic microbes contributes to pathogen resistance is just beginning to be explored. Understanding diversity effects on pathogen resistance could be particularly helpful in combating the fungal pathogen Batrachochytrium dendrobatidis (Bd) which has caused dramatic population declines in many amphibian species and is a major concern for amphibian conservation. Our study investigates the ability of host-associated bacteria to inhibit the proliferation of Bd when grown in experimentally assembled biofilm communities that differ in species number and composition. Six bacterial species isolated from the skin of Cascades frogs (Rana cascadae) were used to assemble bacterial biofilm communities containing 1, 2, 3, or all 6 bacterial species. Biofilm communities were grown with Bd for 7 days following inoculation. More speciose bacterial communities reduced Bd abundance more effectively. This relationship between bacterial species richness and Bd suppression appeared to be driven by dominance effects-the bacterial species that were most effective at inhibiting Bd dominated multi-species communities-and complementarity: multi-species communities inhibited Bd growth more than monocultures of constituent species. These results underscore the notion that pathogen resistance is an emergent property of microbial communities, a consideration that should be taken into account when designing probiotic treatments to reduce the impacts of infectious disease.

  20. Probiotic E. coli Nissle 1917 biofilms on silicone substrates for bacterial interference against pathogen colonization.

    PubMed

    Chen, Quan; Zhu, Zhiling; Wang, Jun; Lopez, Analette I; Li, Siheng; Kumar, Amit; Yu, Fei; Chen, Haoqing; Cai, Chengzhi; Zhang, Lijuan

    2017-03-01

    Bacterial interference is an alternative strategy to fight against device-associated bacterial infections. Pursuing this strategy, a non-pathogenic bacterial biofilm is used as a live, protective barrier to fence off pathogen colonization. In this work, biofilms formed by probiotic Escherichia coli strain Nissle 1917 (EcN) are investigated for their potential for long-term bacterial interference against infections associated with silicone-based urinary catheters and indwelling catheters used in the digestive system, such as feeding tubes and voice prostheses. We have shown that EcN can form stable biofilms on silicone substrates, particularly those modified with a biphenyl mannoside derivative. These biofilms greatly reduced the colonization by pathogenic Enterococcus faecalis in Lysogeny broth (LB) for 11days.

  1. Extracellular vesicles from Paracoccidioides pathogenic species transport polysaccharide and expose ligands for DC-SIGN receptors

    DOE PAGES

    da Silva, Roberta Peres; Heiss, Christian; Black, Ian; ...

    2015-09-21

    Extracellular vesicles (EVs) mediate non-conventional transport of molecules across the fungal cell wall. We aimed at describing the carbohydrate composition and surface carbohydrate epitopes of EVs isolated from the pathogenic fungi Paracoccidioides brasiliensis and P. lutzii using standard procedures. Total EV carbohydrates were ethanol-precipitated from preparations depleted of lipids and proteins, then analyzed by chemical degradation, gas chromatography-mass spectrometry, nuclear magnetic resonance and size-exclusion chromatography. EV glycosyl residues of Glc, Man, and Gal comprised most probably two major components: a high molecular mass 4,6-α-glucan and a galactofuranosylmannan, possibly an oligomer, bearing a 2-α-Manp main chain linked to β-Galf (1,3) andmore » α-Manp (1,6) end units. The results also suggested the presence of small amounts of a (1→6)- Manp polymer, (1→3)-glucan and (1→6)-glucan. Glycan microarrays allowed identification of EV surface lectin(s), while plant lectin microarray profiling revealed terminal Man and GlcNAc residues exposed at the EVs surface. Mammalian lectin microarray profiling showed that DC-SIGN receptors recognized surface carbohydrate in Paracoccidioides EVs. Our results suggest that oligosaccharides, cytoplasmic storage, and cell wall polysaccharides can be exported in fungal EVs, which also expose surface PAMPs and lectins. As a result, the role of these newly identified components in the interaction with the host remains to be unraveled.« less

  2. Extracellular vesicles from Paracoccidioides pathogenic species transport polysaccharide and expose ligands for DC-SIGN receptors

    PubMed Central

    da Silva, Roberta Peres; Heiss, Christian; Black, Ian; Azadi, Parastoo; Gerlach, Jared Q.; Travassos, Luiz R.; Joshi, Lokesh; Kilcoyne, Michelle; Puccia, Rosana

    2015-01-01

    Extracellular vesicles (EVs) mediate non-conventional transport of molecules across the fungal cell wall. We aimed at describing the carbohydrate composition and surface carbohydrate epitopes of EVs isolated from the pathogenic fungi Paracoccidioides brasiliensis and P. lutzii using standard procedures. Total EV carbohydrates were ethanol-precipitated from preparations depleted of lipids and proteins, then analyzed by chemical degradation, gas chromatography-mass spectrometry, nuclear magnetic resonance and size-exclusion chromatography. EV glycosyl residues of Glc, Man, and Gal comprised most probably two major components: a high molecular mass 4,6-α-glucan and a galactofuranosylmannan, possibly an oligomer, bearing a 2-α-Manp main chain linked to β-Galf (1,3) and α-Manp (1,6) end units. The results also suggested the presence of small amounts of a (1→6)-Manp polymer, (1→3)-glucan and (1→6)-glucan. Glycan microarrays allowed identification of EV surface lectin(s), while plant lectin microarray profiling revealed terminal Man and GlcNAc residues exposed at the EVs surface. Mammalian lectin microarray profiling showed that DC-SIGN receptors recognized surface carbohydrate in Paracoccidioides EVs. Our results suggest that oligosaccharides, cytoplasmic storage, and cell wall polysaccharides can be exported in fungal EVs, which also expose surface PAMPs and lectins. The role of these newly identified components in the interaction with the host remains to be unraveled. PMID:26387503

  3. What Makes a Bacterial Species Pathogenic?:Comparative Genomic Analysis of the Genus Leptospira

    PubMed Central

    Fouts, Derrick E.; Matthias, Michael A.; Adhikarla, Haritha; Adler, Ben; Amorim-Santos, Luciane; Berg, Douglas E.; Bulach, Dieter; Buschiazzo, Alejandro; Chang, Yung-Fu; Galloway, Renee L.; Haake, David A.; Haft, Daniel H.; Hartskeerl, Rudy; Ko, Albert I.; Levett, Paul N.; Matsunaga, James; Mechaly, Ariel E.; Monk, Jonathan M.; Nascimento, Ana L. T.; Nelson, Karen E.; Palsson, Bernhard; Peacock, Sharon J.; Picardeau, Mathieu; Ricaldi, Jessica N.; Thaipandungpanit, Janjira; Wunder, Elsio A.; Yang, X. Frank; Zhang, Jun-Jie; Vinetz, Joseph M.

    2016-01-01

    Leptospirosis, caused by spirochetes of the genus Leptospira, is a globally widespread, neglected and emerging zoonotic disease. While whole genome analysis of individual pathogenic, intermediately pathogenic and saprophytic Leptospira species has been reported, comprehensive cross-species genomic comparison of all known species of infectious and non-infectious Leptospira, with the goal of identifying genes related to pathogenesis and mammalian host adaptation, remains a key gap in the field. Infectious Leptospira, comprised of pathogenic and intermediately pathogenic Leptospira, evolutionarily diverged from non-infectious, saprophytic Leptospira, as demonstrated by the following computational biology analyses: 1) the definitive taxonomy and evolutionary relatedness among all known Leptospira species; 2) genomically-predicted metabolic reconstructions that indicate novel adaptation of infectious Leptospira to mammals, including sialic acid biosynthesis, pathogen-specific porphyrin metabolism and the first-time demonstration of cobalamin (B12) autotrophy as a bacterial virulence factor; 3) CRISPR/Cas systems demonstrated only to be present in pathogenic Leptospira, suggesting a potential mechanism for this clade’s refractoriness to gene targeting; 4) finding Leptospira pathogen-specific specialized protein secretion systems; 5) novel virulence-related genes/gene families such as the Virulence Modifying (VM) (PF07598 paralogs) proteins and pathogen-specific adhesins; 6) discovery of novel, pathogen-specific protein modification and secretion mechanisms including unique lipoprotein signal peptide motifs, Sec-independent twin arginine protein secretion motifs, and the absence of certain canonical signal recognition particle proteins from all Leptospira; and 7) and demonstration of infectious Leptospira-specific signal-responsive gene expression, motility and chemotaxis systems. By identifying large scale changes in infectious (pathogenic and intermediately pathogenic

  4. Surface Proteoglycans as Mediators in Bacterial Pathogens Infections

    PubMed Central

    García, Beatriz; Merayo-Lloves, Jesús; Martin, Carla; Alcalde, Ignacio; Quirós, Luis M.; Vazquez, Fernando

    2016-01-01

    Infectious diseases remain an important global health problem. The interaction of a wide range of pathogen bacteria with host cells from many different tissues is frequently mediated by proteoglycans. These compounds are ubiquitous complex molecules which are not only involved in adherence and colonization, but can also participate in other steps of pathogenesis. To overcome the problem of microbial resistance to antibiotics new therapeutic agents could be developed based on the characteristics of the interaction of pathogens with proteoglycans. PMID:26941735

  5. A Novel Extracellular Metallopeptidase Domain Shared by Animal Host-Associated Mutualistic and Pathogenic Microbes

    PubMed Central

    Nakjang, Sirintra; Ndeh, Didier A.; Wipat, Anil; Bolam, David N.; Hirt, Robert P.

    2012-01-01

    The mucosal microbiota is recognised as an important factor for our health, with many disease states linked to imbalances in the normal community structure. Hence, there is considerable interest in identifying the molecular basis of human-microbe interactions. In this work we investigated the capacity of microbes to thrive on mucosal surfaces, either as mutualists, commensals or pathogens, using comparative genomics to identify co-occurring molecular traits. We identified a novel domain we named M60-like/PF13402 (new Pfam entry PF13402), which was detected mainly among proteins from animal host mucosa-associated prokaryotic and eukaryotic microbes ranging from mutualists to pathogens. Lateral gene transfers between distantly related microbes explained their shared M60-like/PF13402 domain. The novel domain is characterised by a zinc-metallopeptidase-like motif and is distantly related to known viral enhancin zinc-metallopeptidases. Signal peptides and/or cell surface anchoring features were detected in most microbial M60-like/PF13402 domain-containing proteins, indicating that these proteins target an extracellular substrate. A significant subset of these putative peptidases was further characterised by the presence of associated domains belonging to carbohydrate-binding module family 5/12, 32 and 51 and other glycan-binding domains, suggesting that these novel proteases are targeted to complex glycoproteins such as mucins. An in vitro mucinase assay demonstrated degradation of mammalian mucins by a recombinant form of an M60-like/PF13402-containing protein from the gut mutualist Bacteroides thetaiotaomicron. This study reveals that M60-like domains are peptidases targeting host glycoproteins. These peptidases likely play an important role in successful colonisation of both vertebrate mucosal surfaces and the invertebrate digestive tract by both mutualistic and pathogenic microbes. Moreover, 141 entries across various peptidase families described in the MEROPS

  6. Comparative proteomic analysis of extracellular secreted proteins expressed by two pathogenic Acanthamoeba castellanii clinical isolates and a non-pathogenic ATCC strain.

    PubMed

    Huang, Jian-Ming; Lin, Wei-Chen; Li, Sung-Chou; Shih, Min-Hsiu; Chan, Wen-Ching; Shin, Jyh-Wei; Huang, Fu-Chin

    2016-07-01

    Acanthamoeba keratitis (AK) is a serious ocular disease caused by pathogenic Acanthamoeba gaining entry through wounds in the corneal injury; generally, patients at risk for contracting AK wear contact lenses, usually over a long period of time. Moreover, pathogenic Acanthamoeba causes serious consequences: it makes the cornea turbid and difficult to operate on, including procedures such as enucleation of the eyeball. At present, diagnosis of this disease is not straightforward, and treatment is very demanding. We have established the comparative transcriptome and extracellular secreted proteomic database according to the non-pathogenic strain ATCC 30010 and the pathogenic strains NCKU_B and NCKU_D. We identified 44 secreted proteins successfully, 10 consensus secreted proteins and 34 strain-specific secreted proteins. These proteins may provide targets for therapy and immuno-diagnosis of Acanthamoeba infections. This study shows a suitable approach to identify secreted proteins in Acanthamoeba and provides new perspectives for the study of molecules potentially involved in the AK.

  7. Genomic and Surface Proteomic Analysis of the Canine Pathogen Staphylococcus pseudintermedius Reveals Proteins That Mediate Adherence to the Extracellular Matrix ▿

    PubMed Central

    Bannoehr, Jeanette; Ben Zakour, Nouri L.; Reglinski, Mark; Inglis, Neil F.; Prabhakaran, Sabitha; Fossum, Even; Smith, David G.; Wilson, Gillian J.; Cartwright, Robyn A.; Haas, Juergen; Hook, Magnus; van den Broek, Adri H. M.; Thoday, Keith L.; Fitzgerald, J. Ross

    2011-01-01

    Cell wall-associated (CWA) proteins made by Gram-positive pathogens play a fundamental role in pathogenesis. Staphylococcus pseudintermedius is a major animal pathogen responsible for the canine skin disease bacterial pyoderma. Here, we describe the bioinformatic analysis of the family of 18 predicted CWA proteins encoded in the genome of S. pseudintermedius strain ED99 and determine their distribution among a phylogenetically diverse panel of S. pseudintermedius clinical isolates and closely related species of the Staphylococcus intermedius group. In parallel, we employed a proteomic approach to identify proteins presented on the surface of strain ED99 in vitro, revealing a total of 60 surface-localized proteins in one or more phases of growth, including 6 of the 18 genome-predicted CWA proteins. Based on these analyses, we selected two CWA proteins (SpsD and SpsL) encoded by all strains examined and investigated their capacity to mediate adherence to extracellular matrix proteins. We discovered that SpsD and SpsL mediated binding of a heterologous host, Lactococcus lactis, to fibrinogen and fibronectin and that SpsD mediated binding to cytokeratin 10, a major constituent of mammalian skin. Of note, the interaction with fibrinogen was host-species dependent, suggestive of a role for SpsD and SpsL in the host tropism of S. pseudintermedius. Finally, we identified IgG specific for SpsD and SpsL in sera from dogs with bacterial pyoderma, implying that both proteins are expressed during infection. The combined genomic and proteomic approach employed in the current study has revealed novel host-pathogen interactions which represent candidate therapeutic targets for the control of bacterial pyoderma. PMID:21576333

  8. Profile and Fate of Bacterial Pathogens in Sewage Treatment Plants Revealed by High-Throughput Metagenomic Approach.

    PubMed

    Li, Bing; Ju, Feng; Cai, Lin; Zhang, Tong

    2015-09-01

    The broad-spectrum profile of bacterial pathogens and their fate in sewage treatment plants (STPs) were investigated using high-throughput sequencing based metagenomic approach. This novel approach could provide a united platform to standardize bacterial pathogen detection and realize direct comparison among different samples. Totally, 113 bacterial pathogen species were detected in eight samples including influent, effluent, activated sludge (AS), biofilm, and anaerobic digestion sludge with the abundances ranging from 0.000095% to 4.89%. Among these 113 bacterial pathogens, 79 species were reported in STPs for the first time. Specially, compared to AS in bulk mixed liquor, more pathogen species and higher total abundance were detected in upper foaming layer of AS. This suggests that the foaming layer of AS might impose more threat to onsite workers and citizens in the surrounding areas of STPs because pathogens in foaming layer are easily transferred into air and cause possible infections. The high removal efficiency (98.0%) of total bacterial pathogens suggests that AS treatment process is effective to remove most bacterial pathogens. Remarkable similarities of bacterial pathogen compositions between influent and human gut indicated that bacterial pathogen profiles in influents could well reflect the average bacterial pathogen communities of urban resident guts within the STP catchment area.

  9. Bacteriophage Amplification-Coupled Detection and Identification of Bacterial Pathogens

    NASA Astrophysics Data System (ADS)

    Cox, Christopher R.; Voorhees, Kent J.

    Current methods of species-specific bacterial detection and identification are complex, time-consuming, and often require expensive specialized equipment and highly trained personnel. Numerous biochemical and genotypic identification methods have been applied to bacterial characterization, but all rely on tedious microbiological culturing practices and/or costly sequencing protocols which render them impractical for deployment as rapid, cost-effective point-of-care or field detection and identification methods. With a view towards addressing these shortcomings, we have exploited the evolutionarily conserved interactions between a bacteriophage (phage) and its bacterial host to develop species-specific detection methods. Phage amplification-coupled matrix assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF-MS) was utilized to rapidly detect phage propagation resulting from species-specific in vitro bacterial infection. This novel signal amplification method allowed for bacterial detection and identification in as little as 2 h, and when combined with disulfide bond reduction methods developed in our laboratory to enhance MALDI-TOF-MS resolution, was observed to lower the limit of detection by several orders of magnitude over conventional spectroscopy and phage typing methods. Phage amplification has been combined with lateral flow immunochromatography (LFI) to develop rapid, easy-to-operate, portable, species-specific point-of-care (POC) detection devices. Prototype LFI detectors have been developed and characterized for Yersinia pestis and Bacillus anthracis, the etiologic agents of plague and anthrax, respectively. Comparable sensitivity and rapidity was observed when phage amplification was adapted to a species-specific handheld LFI detector, thus allowing for rapid, simple, POC bacterial detection and identification while eliminating the need for bacterial culturing or DNA isolation and amplification techniques.

  10. Mixed biofilm formation by Shiga toxin-producing Escherichia coli and Salmonella enterica serovar Typhimurium enhanced bacterial resistance to sanitization due to extracellular polymeric substances.

    PubMed

    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.

  11. Microbiome analysis reveals the abundance of bacterial pathogens in Rousettus leschenaultii guano

    PubMed Central

    Banskar, Sunil; Bhute, Shrikant S.; Suryavanshi, Mangesh V.; Punekar, Sachin; Shouche, Yogesh S.

    2016-01-01

    Bats are crucial for proper functioning of an ecosystem. They provide various important services to ecosystem and environment. While, bats are well-known carrier of pathogenic viruses, their possible role as a potential carrier of pathogenic bacteria is under-explored. Here, using culture-based approach, employing multiple bacteriological media, over thousand bacteria were cultivated and identified from Rousettus leschenaultii (a frugivorous bat species), the majority of which were from the family Enterobacteriaceae and putative pathogens. Next, pathogenic potential of most frequently cultivated component of microbiome i.e. Escherichia coli was assessed to identify its known pathotypes which revealed the presence of virulent factors in many cultivated E. coli isolates. Applying in-depth bacterial community analysis using high-throughput 16 S rRNA gene sequencing, a high inter-individual variation was observed among the studied guano samples. Interestingly, a higher diversity of bacterial communities was observed in decaying guano representative. The search against human pathogenic bacteria database at 97% identity, a small proportion of sequences were found associated to well-known human pathogens. The present study thus indicates that this bat species may carry potential bacterial pathogens and advice to study the effect of these pathogens on bats itself and the probable mode of transmission to humans and other animals. PMID:27845426

  12. CorA, the magnesium/nickel/cobalt transporter, affects virulence and extracellular enzyme production in the soft rot pathogen Pectobacterium carotovorum.

    PubMed

    Kersey, Caleb M; Agyemang, Paul A; Dumenyo, C Korsi

    2012-01-01

    Pectobacterium carotovorum (formerly Erwinia carotovora ssp. carotovora) is a phytopathogenic bacterium that causes soft rot disease, characterized by water-soaked soft decay, resulting from the action of cell wall-degrading exoenzymes secreted by the pathogen. Virulence in soft rot bacteria is regulated by environmental factors, host and bacterial chemical signals, and a network of global and gene-specific bacterial regulators. We isolated a mini-Tn5 mutant of P. carotovorum that is reduced in the production of extracellular pectate lyase, protease, polygalacturonase and cellulase. The mutant is also decreased in virulence as it macerates less host tissues than its parent and is severely impaired in multiplication in planta. The inactivated gene responsible for the reduced virulent phenotype was identified as corA. CorA, a magnesium/nickel/cobalt membrane transporter, is the primary magnesium transporter for many bacteria. Compared with the parent, the CorA(-) mutant is cobalt resistant. The mutant phenotype was confirmed in parental strain P. carotovorum by marker exchange inactivation of corA. A functional corA(+) DNA from P. carotovorum restored exoenzyme production and pathogenicity to the mutants. The P. carotovorum corA(+) clone also restored motility and cobalt sensitivity to a CorA(-) mutant of Salmonella enterica. These data indicate that CorA is required for exoenzyme production and virulence in P. carotovorum.

  13. The Enteric Two-Step: nutritional strategies of bacterial pathogens within the gut

    PubMed Central

    Ferreyra, Jessica A.; Ng, Katharine M.; Sonnenburg, Justin L.

    2016-01-01

    Summary The gut microbiota is a dense and diverse microbial community governed by dynamic microbe–microbe and microbe–host interactions, the status of which influences whether enteric pathogens can cause disease. Here we review recent insights into the key roles that nutrients play in bacterial pathogen exploitation of the gut microbial ecosystem. We synthesize recent findings to support a five-stage model describing the transition between a healthy microbiota and one dominated by a pathogen and disease. Within this five-stage model, two stages are critical to the pathogen: (i) an initial expansion phase that must occur in the absence of pathogen-induced inflammation, followed by (ii) pathogen-promoting physiological changes such as inflammation and diarrhoea. We discuss how this emerging paradigm of pathogen life within the lumen of the gut is giving rise to novel therapeutic strategies. PMID:24720567

  14. From cholera to corals: Viruses as drivers of virulence in a major coral bacterial pathogen

    PubMed Central

    Weynberg, Karen D.; Voolstra, Christian R.; Neave, Matthew J.; Buerger, Patrick; van Oppen, Madeleine J. H.

    2015-01-01

    Disease is an increasing threat to reef-building corals. One of the few identified pathogens of coral disease is the bacterium Vibrio coralliilyticus. In Vibrio cholerae, infection by a bacterial virus (bacteriophage) results in the conversion of non-pathogenic strains to pathogenic strains and this can lead to cholera pandemics. Pathogenicity islands encoded in the V. cholerae genome play an important role in pathogenesis. Here we analyse five whole genome sequences of V. coralliilyticus to examine whether virulence is similarly driven by horizontally acquired elements. We demonstrate that bacteriophage genomes encoding toxin genes with homology to those found in pathogenic V. cholerae are integrated in V. coralliilyticus genomes. Virulence factors located on chromosomal pathogenicity islands also exist in some strains of V. coralliilyticus. The presence of these genetic signatures indicates virulence in V. coralliilyticus is driven by prophages and other horizontally acquired elements. Screening for pathogens of coral disease should target conserved regions in these elements. PMID:26644037

  15. Adhesion of bacterial pathogens to soil colloidal particles: influences of cell type, natural organic matter, and solution chemistry.

    PubMed

    Zhao, Wenqiang; Walker, Sharon L; Huang, Qiaoyun; Cai, Peng

    2014-04-15

    Bacterial adhesion to granular soil particles is well studied; however, pathogen interactions with naturally occurring colloidal particles (<2 μm) in soil has not been investigated. This study was developed to identify the interaction mechanisms between model bacterial pathogens and soil colloids as a function of cell type, natural organic matter (NOM), and solution chemistry. Specifically, batch adhesion experiments were conducted using NOM-present, NOM-stripped soil colloids, Streptococcus suis SC05 and Escherichia coli WH09 over a wide range of solution pH (4.0-9.0) and ionic strength (IS, 1-100 mM KCl). Cell characterization techniques, Freundlich isotherm, and Derjaguin-Landau-Verwey-Overbeek (DLVO) theory (sphere-sphere model) were utilized to quantitatively determine the interactions between cells and colloids. The adhesion coefficients (Kf) of S. suis SC05 to NOM-present and NOM-stripped soil colloids were significantly higher than E. coli WH09, respectively. Similarly, Kf values of S. suis SC05 and E. coli WH09 adhesion to NOM-stripped soil colloids were greater than those colloids with NOM-present, respectively, suggesting NOM inhibits bacterial adhesion. Cell adhesion to soil colloids declined with increasing pH and enhanced with rising IS (1-50 mM). Interaction energy calculations indicate these adhesion trends can be explained by DLVO-type forces, with S. suis SC05 and E. coli WH09 being weakly adhered in shallow secondary energy minima via polymer bridging and charge heterogeneity. S. suis SC05 adhesion decreased at higher IS 100 mM, which is attributed to the change of hydrophobic effect and steric repulsion resulted from the greater presence of extracellular polymeric substances (EPS) on S. suis SC05 surface as compared to E. coli WH09. Hence, pathogen adhesion to the colloidal material is determined by a combination of DLVO, charge heterogeneity, hydrophobic and polymer interactions as a function of solution chemistry.

  16. Vaccine strategies against bacterial pathogens in cystic fibrosis patients.

    PubMed

    Le Moigne, V; Gaillard, J-L; Herrmann, J-L

    2016-02-01

    A large number of cystic fibrosis pathogens such as bacteria of the Burkholderia cepacia complex, Pseudomonas aeruginosa, or Mycobacterium abscessus are associated with complex therapeutic problems due to their inherent resistance to antibiotics. No vaccine is currently available against those pathogens. Vaccines are therefore crucial to combat these multidrug-resistant bacteria in specific clinical situations including cystic fibrosis. Various strategies may be considered to develop these vaccines. Similar virulence factors are expressed during the infection with various pathogens; they could thus be used as antigen to assess cross-protection. Many clinical trials are currently being conducted to try and develop a prophylactic treatment for patients presenting with cystic fibrosis. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  17. Two apextrin-like proteins mediate extracellular and intracellular bacterial recognition in amphioxus.

    PubMed

    Huang, Guangrui; Huang, Shengfeng; Yan, Xinyu; Yang, Ping; Li, Jun; Xu, Weiya; Zhang, Lingling; Wang, Ruihua; Yu, Yingcai; Yuan, Shaochun; Chen, Shangwu; Luo, Guangbin; Xu, Anlong

    2014-09-16

    Animals exploit different germ-line-encoded proteins with various domain structures to detect the signature molecules of pathogenic microbes. These molecules are known as pathogen-associated molecular patterns (PAMPs), and the host proteins that react with PAMPs are called pattern recognition proteins (PRPs). Here, we present a novel type of protein domain structure capable of binding to bacterial peptidoglycan (PGN) and the minimal PGN motif muramyl dipeptide (MDP). This domain is designated as apextrin C-terminal domain (ApeC), and its presence was confirmed in several invertebrate phyla and subphyla. Two apextrin-like proteins (ALP1 and ALP2) were identified in a basal chordate, the Japanese amphioxus Branchiostoma japonicum (bj). bjALP1 is a mucosal effector secreted into the gut lumen to agglutinate the Gram-positive bacterium Staphylococcus aureus via PGN binding. Neutralization of secreted bjALP1 by anti-bjALP1 monoclonal antibodies caused serious damage to the gut epithelium and rapid death of the animals after bacterial infection. bjALP2 is an intracellular PGN sensor that binds to TNF receptor-associated factor 6 (TRAF6) and prevents TRAF6 from self-ubiquitination and hence from NF-κB activation. MDP was found to compete with TRAF6 for bjALP2, which released TRAF6 to activate the NF-κB pathway. BjALP1 and bjALP2 therefore play distinct and complementary functions in amphioxus gut mucosal immunity. In conclusion, discovery of the ApeC domain and the functional analyses of amphioxus ALP1 and ALP2 allowed us to define a previously undocumented type of PRP that is represented across different animal phyla.

  18. Cell-to-Cell Propagation of the Bacterial Toxin CNF1 via Extracellular Vesicles: Potential Impact on the Therapeutic Use of the Toxin

    PubMed Central

    Fabbri, Alessia; Cori, Sara; Zanetti, Cristiana; Guidotti, Marco; Sargiacomo, Massimo; Loizzo, Stefano; Fiorentini, Carla

    2015-01-01

    Eukaryotic cells secrete extracellular vesicles (EVs), either constitutively or in a regulated manner, which represent an important mode of intercellular communication. EVs serve as vehicles for transfer between cells of membrane and cytosolic proteins, lipids and RNA. Furthermore, certain bacterial protein toxins, or possibly their derived messages, can be transferred cell to cell via EVs. We have herein demonstrated that eukaryotic EVs represent an additional route of cell-to-cell propagation for the Escherichia coli protein toxin cytotoxic necrotizing factor 1 (CNF1). Our results prove that EVs from CNF1 pre-infected epithelial cells can induce cytoskeleton changes, Rac1 and NF-κB activation comparable to that triggered by CNF1. The observation that the toxin is detectable inside EVs derived from CNF1-intoxicated cells strongly supports the hypothesis that extracellular vesicles can offer to the toxin a novel route to travel from cell to cell. Since anthrax and tetanus toxins have also been reported to engage in the same process, we can hypothesize that EVs represent a common mechanism exploited by bacterial toxins to enhance their pathogenicity. PMID:26556375

  19. LAP, an alcohol acetaldehyde dehydrogenase enzyme in Listeria, promotes bacterial adhesion to enterocyte-like Caco-2 cells only in pathogenic species.

    PubMed

    Jagadeesan, Balamurugan; Koo, Ok Kyung; Kim, Kwang-Pyo; Burkholder, Kristin M; Mishra, Krishna K; Aroonnual, Amornrat; Bhunia, Arun K

    2010-09-01

    Listeria adhesion protein (LAP), an alcohol acetaldehyde dehydrogenase (lmo1634), interacts with host-cell receptor Hsp60 to promote bacterial adhesion during the intestinal phase of Listeria monocytogenes infection. The LAP homologue is present in pathogens (L. monocytogenes, L. ivanovii) and non-pathogens (L. innocua, L. welshimeri, L. seeligeri); however, its role in non-pathogens is unknown. Sequence analysis revealed 98 % amino acid similarity in LAP from all Listeria species. The N-terminus contains acetaldehyde dehydrogenase (ALDH) and the C-terminus an alcohol dehydrogenase (ADH). Recombinant LAP from L. monocytogenes, L. ivanovii, L. innocua and L. welshimeri exhibited ALDH and ADH activities, and displayed strong binding affinity (K(D) 2-31 nM) towards Hsp60. Flow cytometry, ELISA and immunoelectron microscopy revealed more surface-associated LAP in pathogens than non-pathogens. Pathogens exhibited significantly higher adhesion (P<0.05) to Caco-2 cells than non-pathogens; however, pretreatment of bacteria with Hsp60 caused 47-92 % reduction in adhesion only in pathogens. These data suggest that biochemical properties of LAP from pathogenic Listeria are similar to those of the protein from non-pathogens in many respects, such as substrate specificity, immunogenicity, and binding affinity to Hsp60. However, protein fractionation analysis of extracts from pathogenic and non-pathogenic Listeria species revealed that LAP was greatly reduced in intracellular and cell-surface protein fractions, and undetectable in the extracellular milieu of non-pathogens even though the lap transcript levels were similar for both. Furthermore, a LAP preparation from L. monocytogenes restored adhesion in a lap mutant (KB208) of L. monocytogenes but not in L. innocua, indicating possible lack of surface reassociation of LAP molecules in this bacterium. Taken together, these data suggest that LAP expression level, cell-surface localization, secretion and reassociation are

  20. Challenge of investigating biologically relevant functions of virulence factors in bacterial pathogens.

    PubMed Central

    Moxon, R; Tang, C

    2000-01-01

    Recent innovations have increased enormously the opportunities for investigating the molecular basis of bacterial pathogenicity, including the availability of whole-genome sequences, techniques for identifying key virulence genes, and the use of microarrays and proteomics. These methods should provide powerful tools for analysing the patterns of gene expression and function required for investigating host-microbe interactions in vivo. But, the challenge is exacting. Pathogenicity is a complex phenotype and the reductionist approach does not adequately address the eclectic and variable outcomes of host-microbe interactions, including evolutionary dynamics and ecological factors. There are difficulties in distinguishing bacterial 'virulence' factors from the many determinants that are permissive for pathogenicity, for example those promoting general fitness. A further practical problem for some of the major bacterial pathogens is that there are no satisfactory animal models or experimental assays that adequately reflect the infection under investigation. In this review, we give a personal perspective on the challenge of characterizing how bacterial pathogens behave in vivo and discuss some of the methods that might be most relevant for understanding the molecular basis of the diseases for which they are responsible. Despite the powerful genomic, molecular, cellular and structural technologies available to us, we are still struggling to come to grips with the question of 'What is a pathogen?' PMID:10874737

  1. Hijacking Host Cell Highways: Manipulation of the Host Actin Cytoskeleton by Obligate Intracellular Bacterial Pathogens

    PubMed Central

    Colonne, Punsiri M.; Winchell, Caylin G.; Voth, Daniel E.

    2016-01-01

    Intracellular bacterial pathogens replicate within eukaryotic cells and display unique adaptations that support key infection events including invasion, replication, immune evasion, and dissemination. From invasion to dissemination, all stages of the intracellular bacterial life cycle share the same three-dimensional cytosolic space containing the host cytoskeleton. For successful infection and replication, many pathogens hijack the cytoskeleton using effector proteins introduced into the host cytosol by specialized secretion systems. A subset of effectors contains eukaryotic-like motifs that mimic host proteins to exploit signaling and modify specific cytoskeletal components such as actin and microtubules. Cytoskeletal rearrangement promotes numerous events that are beneficial to the pathogen, including internalization of bacteria, structural support for bacteria-containing vacuoles, altered vesicular trafficking, actin-dependent bacterial movement, and pathogen dissemination. This review highlights a diverse group of obligate intracellular bacterial pathogens that manipulate the host cytoskeleton to thrive within eukaryotic cells and discusses underlying molecular mechanisms that promote these dynamic host-pathogen interactions. PMID:27713866

  2. Development and application of the active surveillance of pathogens microarray to monitor bacterial gene flux

    PubMed Central

    Stabler, Richard A; Dawson, Lisa F; Oyston, Petra CF; Titball, Richard W; Wade, Jim; Hinds, Jason; Witney, Adam A; Wren, Brendan W

    2008-01-01

    Background Human and animal health is constantly under threat by emerging pathogens that have recently acquired genetic determinants that enhance their survival, transmissibility and virulence. We describe the construction and development of an Active Surveillance of Pathogens (ASP) oligonucleotide microarray, designed to 'actively survey' the genome of a given bacterial pathogen for virulence-associated genes. Results The microarray consists of 4958 reporters from 151 bacterial species and include genes for the identification of individual bacterial species as well as mobile genetic elements (transposons, plasmid and phage), virulence genes and antibiotic resistance genes. The ASP microarray was validated with nineteen bacterial pathogens species, including Francisella tularensis, Clostridium difficile, Staphylococcus aureus, Enterococcus faecium and Stenotrophomonas maltophilia. The ASP microarray identified these bacteria, and provided information on potential antibiotic resistance (eg sufamethoxazole resistance and sulfonamide resistance) and virulence determinants including genes likely to be acquired by horizontal gene transfer (e.g. an alpha-haemolysin). Conclusion The ASP microarray has potential in the clinic as a diagnostic tool, as a research tool for both known and emerging pathogens, and as an early warning system for pathogenic bacteria that have been recently modified either naturally or deliberately. PMID:18844996

  3. Assets of the non-pathogenic microorganism Dictyostelium discoideum as a model for the study of eukaryotic extracellular vesicles.

    PubMed

    Tatischeff, Irène

    2013-01-01

    Dictyostelium discoideum microvesicles have recently been presented as a valuable model for eukaryotic extracellular vesicles. Here, the advantages of D. discoideum for unraveling important biological functions of extracellular vesicles in general are detailed. D. discoideum, a non-pathogenic eukaryotic microorganism, belongs to a billion-year-old Amoeboza lineage, which diverged from the animal-fungal lineage after the plant animal-split. During growth and early starvation-induced development, it presents analogies with lymphocytes and macrophages with regard to motility and phagocytosis capability, respectively. Its 6-chromosome genome codes for about 12,500 genes, some showing analogies with human genes. The presence of extracellular vesicles during cell growth has been evidenced as a detoxification mechanism of various structurally unrelated drugs. Controls led to the discovery of constitutive extracellular vesicle secretion in this microorganism, which was an important point. It means that the secretion of extracellular vesicles occurs, in the absence of any drug, during both cell growth and early development. This constitutive secretion of D. discoideum cells is very likely to play a role in intercellular communication. The detoxifying secreted vesicles, which can transport drugs outside the cells, can also act as "Trojan horses", capable of transferring these drugs not only into naïve D. discoideum cells, but into human cells as well. Therefore, these extracellular vesicles were proposed as a new biological drug delivery tool. Moreover, Dictyostelium, chosen by the NIH (USA) as a new model organism for biomedical research, has already been used for studying some human diseases. These cells, which are much easier to manipulate than human cells, can be easily designed in simple conditioned medium experiments. Owing to the increasing consensus that extracellular vesicles are probably important mediators of intercellular communication, D. discoideum is here

  4. Assets of the non-pathogenic microorganism Dictyostelium discoideum as a model for the study of eukaryotic extracellular vesicles.

    PubMed

    Tatischeff, Irène

    2013-03-04

    Dictyostelium discoideum microvesicles have recently been presented as a valuable model for eukaryotic extracellular vesicles. Here, the advantages of D. discoideum for unraveling important biological functions of extracellular vesicles in general are detailed. D. discoideum, a non-pathogenic eukaryotic microorganism, belongs to a billion-year-old Amoeboza lineage, which diverged from the animal-fungal lineage after the plant animal-split. During growth and early starvation-induced development, it presents analogies with lymphocytes and macrophages with regard to motility and phagocytosis capability, respectively. Its 6-chromosome genome codes for about 12,500 genes, some showing analogies with human genes. The presence of extracellular vesicles during cell growth has been evidenced as a detoxification mechanism of various structurally unrelated drugs. Controls led to the discovery of constitutive extracellular vesicle secretion in this microorganism, which was an important point. It means that the secretion of extracellular vesicles occurs, in the absence of any drug, during both cell growth and early development. This constitutive secretion of D. discoideum cells is very likely to play a role in intercellular communication. The detoxifying secreted vesicles, which can transport drugs outside the cells, can also act as "Trojan horses", capable of transferring these drugs not only into naïve D. discoideum cells, but into human cells as well. Therefore, these extracellular vesicles were proposed as a new biological drug delivery tool. Moreover, Dictyostelium, chosen by the NIH (USA) as a new model organism for biomedical research, has already been used for studying some human diseases. These cells, which are much easier to manipulate than human cells, can be easily designed in simple conditioned medium experiments. Owing to the increasing consensus that extracellular vesicles are probably important mediators of intercellular communication, D. discoideum is here

  5. A case study of a bacterial pathogen in irrigation water

    USDA-ARS?s Scientific Manuscript database

    This chapter presents a case study of how exotic strains of Ralstonia solanacearum were disseminated throughout Europe and Florida via waterways used for irrigation. Several studies have demonstrated that aquatic weeds that commonly grow in rivers and ponds are able to harbor the pathogen and allow ...

  6. Effects of Growth Phase and Extracellular Slime on Photodynamic Inactivation of Gram-Positive Pathogenic Bacteria

    PubMed Central

    Gad, Faten; Zahra, Touqir; Hasan, Tayyaba; Hamblin, Michael R.

    2004-01-01

    The emergence of antibiotic resistance among pathogenic bacteria has led to efforts to find alternative antimicrobial therapeutics to which bacteria will not be easily able to develop resistance. One of these may be the combination of nontoxic dyes (photosensitizers [PS]) and visible light, known as photodynamic therapy, and we have reported its use to treat localized infections in animal models. While it is known that gram-positive species are generally susceptible to photodynamic inactivation (PDI), the factors that govern variation in degrees of killing are unknown. We used isogenic pairs of wild-type and transposon mutants deficient in capsular polysaccharide and slime production generated from Staphylococcus epidermidis and Staphylococcus aureus to examine the effects of extracellular slime on susceptibility to PDI mediated by two cationic PS (a polylysine-chlorine6 conjugate, pL-ce6, and methylene blue [MB]) and an anionic molecule, free ce6, and subsequent exposure to 665-nm light at 0 to 40 J/cm2. Free ce6 gave more killing of mutant strains than wild type, despite the latter taking up more PS. Log-phase cultures were killed more than stationary-phase cultures, and this correlated with increased uptake. The cationic pL-ce6 and MB gave similar uptakes and killing despite a 50-fold difference in incubation concentration. Differences in susceptibility between strains and between growth phases observed with free ce6 largely disappeared with the cationic compounds despite significant differences in uptake. These data suggest that slime production and stationary phase can be obstacles against PDI for gram-positive bacteria but that these obstacles can be overcome by using cationic PS. PMID:15155218

  7. The pathogenic fungus Paracoccidioides brasiliensis exports extracellular vesicles containing highly immunogenic α-Galactosyl epitopes.

    PubMed

    Vallejo, Milene C; Matsuo, Alisson L; Ganiko, Luciane; Medeiros, Lia C Soares; Miranda, Kildare; Silva, Luiz S; Freymüller-Haapalainen, Edna; Sinigaglia-Coimbra, Rita; Almeida, Igor C; Puccia, Rosana

    2011-03-01

    Exosome-like vesicles containing virulence factors, enzymes, and antigens have recently been characterized in fungal pathogens, such as Cryptococcus neoformans and Histoplasma capsulatum. Here, we describe extracellular vesicles carrying highly immunogenic α-linked galactopyranosyl (α-Gal) epitopes in Paracoccidioides brasiliensis. P. brasiliensis is a dimorphic fungus that causes human paracoccidioidomycosis (PCM). For vesicle preparations, cell-free supernatant fluids from yeast cells cultivated in Ham's defined medium-glucose were concentrated in an Amicon ultrafiltration system and ultracentrifuged at 100,000 × g. P. brasiliensis antigens were present in preparations from phylogenetically distinct isolates Pb18 and Pb3, as observed in immunoblots revealed with sera from PCM patients. In an enzyme-linked immunosorbent assay (ELISA), vesicle components containing α-Gal epitopes reacted strongly with anti-α-Gal antibodies isolated from both Chagas' disease and PCM patients, with Marasmius oreades agglutinin (MOA) (a lectin that recognizes terminal α-Gal), but only faintly with natural anti-α-Gal. Reactivity was inhibited after treatment with α-galactosidase. Vesicle preparations analyzed by electron microscopy showed vesicular structures of 20 to 200 nm that were labeled both on the surface and in the lumen with MOA. In P. brasiliensis cells, components carrying α-Gal epitopes were found distributed on the cell wall, following a punctuated confocal pattern, and inside large intracellular vacuoles. Lipid-free vesicle fractions reacted with anti-α-Gal in ELISA only when not digested with α-galactosidase, while reactivity with glycoproteins was reduced after β-elimination, which is indicative of partial O-linked chain localization. Our findings open new areas to explore in terms of host-parasite relationships in PCM and the role played in vivo by vesicle components and α-galactosyl epitopes.

  8. Direct detection of various pathogens by loop-mediated isothermal amplification assays on bacterial culture and bacterial colony.

    PubMed

    Yan, Muxia; Li, Weidong; Zhou, Zhenwen; Peng, Hongxia; Luo, Ziyan; Xu, Ling

    2017-01-01

    In this work, loop-mediated isothermal amplification based detection assay using bacterial culture and bacterial colony for various common pathogens direct detection had been established, evaluated and further applied. A total of five species of common pathogens and nine detection targets (tlh, tdh and trh for V. Parahaemolyticus, rfbE, stx1 and stx2 for E. coli, oprI for P. aeruginosa, invA for Salmonella and hylA for L. monocytogenes) were performed on bacterial culture and bacterial colony LAMP. To evaluate and optimize this assay, a total of 116 standard strains were included. Then, for each detected targets, 20 random selected strains were applied. Results were determined through both visual observation of the changed color by naked eye and electrophoresis, which increased the accuracy of survey. The minimum adding quantity of each primer had been confirmed, and the optimal amplification was obtained under 65 °C for 45 min with 25 μl reaction volume. The detection limit of bacterial culture LAMP and PCR assay were determined to be 10(2) and 10(4) or 10(5) CFU/reaction, respectively. No false positive amplification was observed when subjecting the bacterial -LAMP assay to 116 reference strains. This was the first report of colony-LAMP and culture-LAMP assay, which had been demonstrated to be a fast, reliable, cost-effective and simple method on detection of various common pathogens.

  9. Molecular analysis for screening human bacterial pathogens in municipal wastewater treatment and reuse.

    PubMed

    Kumaraswamy, Rajkumari; Amha, Yamrot M; Anwar, Muhammad Z; Henschel, Andreas; Rodríguez, Jorge; Ahmad, Farrukh

    2014-10-07

    Effective and sensitive monitoring of human pathogenic bacteria in municipal wastewater treatment is important not only for managing public health risk related to treated wastewater reuse, but also for ensuring proper functioning of the treatment plant. In this study, three different 16S rRNA gene molecular analysis methodologies were employed to screen bacterial pathogens in samples collected at three different stages of an activated sludge plant. Overall bacterial diversity was analyzed using next generation sequencing (NGS) on the Illumina MiSeq platform, as well as PCR-DGGE followed by band sequencing. In addition, a microdiversity analysis was conducted using PCR-DGGE, targeting Escherichia coli. Bioinformatics analysis was performed using QIIME protocol by clustering sequences against the Human Pathogenic Bacteria Database. NGS data were also clustered against the Greengenes database for a genera-level diversity analysis. NGS proved to be the most effective approach screening the sequences of 21 potential human bacterial pathogens, while the E. coli microdiversity analysis yielded one (O157:H7 str. EDL933) out of the two E. coli strains picked up by NGS. Overall diversity using PCR-DGGE did not yield any pathogenic sequence matches even though a number of sequences matched the NGS results. Overall, sequences of Gram-negative pathogens decreased in relative abundance along the treatment train while those of Gram-positive pathogens increased.

  10. Importance of Soil Amendments: Survival of Bacterial Pathogens in Manure and Compost Used as Organic Fertilizers.

    PubMed

    Sharma, Manan; Reynnells, Russell

    2016-08-01

    Biological soil amendments (BSAs) such as manure and compost are frequently used as organic fertilizers to improve the physical and chemical properties of soils. However, BSAs have been known to be a reservoir for enteric bacterial pathogens such as enterohemorrhagic Escherichia coli (EHEC), Salmonella spp., and Listeria spp. There are numerous mechanisms by which manure may transfer pathogens to growing fruits and vegetables, and several outbreaks of infections have been linked to manure-related contamination of leafy greens. In the United States several commodity-specific guidelines and current and proposed federal rules exist to provide guidance on the application of BSAs as fertilizers to soils, some of which require an interval between the application of manure to soils and the harvest of fruits and vegetables. This review examines the survival, persistence, and regrowth/resuscitation of bacterial pathogens in manure, biosolids, and composts. Moisture, along with climate and the physicochemical properties of soil, manure, or compost, plays a significant role in the ability of pathogens to persist and resuscitate in amended soils. Adaptation of enteric bacterial pathogens to the nonhost environment of soils may also extend their persistence in manure- or compost-amended soils. The presence of antibiotic-resistance genes in soils may also be increased by manure application. Overall, BSAs applied as fertilizers to soils can support the survival and regrowth of pathogens. BSAs should be handled and applied in a manner that reduces the prevalence of pathogens in soils and the likelihood of transfer of food-borne pathogens to fruits and vegetables. This review will focus on two BSAs-raw manure and composted manure (and other feedstocks)-and predominantly on the survival of enteric bacterial pathogens in BSAs as applied to soils as organic fertilizers.

  11. Bacteriophages for detection and control of bacterial pathogens in food and food-processing environment.

    PubMed

    Brovko, Lubov Y; Anany, Hany; Griffiths, Mansel W

    2012-01-01

    This chapter presents recent advances in bacteriophage research and their application in the area of food safety. Section 1 describes general facts on phage biology that are relevant to their application for control and detection of bacterial pathogens in food and environmental samples. Section 2 summarizes the recently acquired data on application of bacteriophages to control growth of bacterial pathogens and spoilage organisms in food and food-processing environment. Section 3 deals with application of bacteriophages for detection and identification of bacterial pathogens. Advantages of bacteriophage-based methods are presented and their shortcomings are discussed. The chapter is intended for food scientist and food product developers, and people in food inspection and health agencies with the ultimate goal to attract their attention to the new developing technology that has a tremendous potential in providing means for producing wholesome and safe food.

  12. The FUN of identifying gene function in bacterial pathogens; insights from Salmonella functional genomics.

    PubMed

    Hammarlöf, Disa L; Canals, Rocío; Hinton, Jay C D

    2013-10-01

    The availability of thousands of genome sequences of bacterial pathogens poses a particular challenge because each genome contains hundreds of genes of unknown function (FUN). How can we easily discover which FUN genes encode important virulence factors? One solution is to combine two different functional genomic approaches. First, transcriptomics identifies bacterial FUN genes that show differential expression during the process of mammalian infection. Second, global mutagenesis identifies individual FUN genes that the pathogen requires to cause disease. The intersection of these datasets can reveal a small set of candidate genes most likely to encode novel virulence attributes. We demonstrate this approach with the Salmonella infection model, and propose that a similar strategy could be used for other bacterial pathogens.

  13. A Plant Bacterial Pathogen Manipulates Its Insect Vector's Energy Metabolism.

    PubMed

    Killiny, Nabil; Hijaz, Faraj; Ebert, Timothy A; Rogers, Michael E

    2017-03-01

    Insect-transmitted plant-pathogenic bacteria may alter their vectors' fitness, survival, behavior, and metabolism. Because these pathogens interact with their vectors on the cellular and organismal levels, potential changes at the biochemical level might occur. "Candidatus Liberibacter asiaticus" (CLas) is transmitted in a persistent, circulative, and propagative manner. The genome of CLas revealed the presence of an ATP translocase that mediates the uptake of ATP and other nucleotides from medium to achieve its biological processes, such as growth and multiplication. Here, we showed that the levels of ATP and many other nucleotides were significantly higher in CLas-infected than healthy psyllids. Gene expression analysis showed upregulation for ATP synthase subunits, while ATPase enzyme activity showed a decrease in ATPase activity. These results indicated that CLas stimulated Diaphorina citri to produce more ATP and many other energetic nucleotides, while it may inhibit their consumption by the insect. As a result of ATP accumulation, the adenylated energy charge (AEC) increased and the AMP/ATP and ADP/ATP ratios decreased in CLas-infected D. citri psyllids. Survival analysis confirmed a shorter life span for CLas-infected D. citri psyllids. In addition, electropenetrography showed a significant reduction in total nonprobing time, salivation time, and time from the last E2 (phloem ingestion) to the end of recording, indicating that CLas-infected psyllids were at a higher hunger level and they tended to forage more often. This increased feeding activity reflects the CLas-induced energetic stress. In conclusion, CLas alters the energy metabolism of its psyllid vector, D. citri, in order to secure its need for energetic nucleotides.IMPORTANCE Insect transmission of plant-pathogenic bacteria involves propagation and circulation of the bacteria within their vectors. The transmission process is complex and requires specific interactions at the molecular and biochemical

  14. A Plant Bacterial Pathogen Manipulates Its Insect Vector's Energy Metabolism

    PubMed Central

    Hijaz, Faraj; Ebert, Timothy A.; Rogers, Michael E.

    2016-01-01

    ABSTRACT Insect-transmitted plant-pathogenic bacteria may alter their vectors' fitness, survival, behavior, and metabolism. Because these pathogens interact with their vectors on the cellular and organismal levels, potential changes at the biochemical level might occur. “Candidatus Liberibacter asiaticus” (CLas) is transmitted in a persistent, circulative, and propagative manner. The genome of CLas revealed the presence of an ATP translocase that mediates the uptake of ATP and other nucleotides from medium to achieve its biological processes, such as growth and multiplication. Here, we showed that the levels of ATP and many other nucleotides were significantly higher in CLas-infected than healthy psyllids. Gene expression analysis showed upregulation for ATP synthase subunits, while ATPase enzyme activity showed a decrease in ATPase activity. These results indicated that CLas stimulated Diaphorina citri to produce more ATP and many other energetic nucleotides, while it may inhibit their consumption by the insect. As a result of ATP accumulation, the adenylated energy charge (AEC) increased and the AMP/ATP and ADP/ATP ratios decreased in CLas-infected D. citri psyllids. Survival analysis confirmed a shorter life span for CLas-infected D. citri psyllids. In addition, electropenetrography showed a significant reduction in total nonprobing time, salivation time, and time from the last E2 (phloem ingestion) to the end of recording, indicating that CLas-infected psyllids were at a higher hunger level and they tended to forage more often. This increased feeding activity reflects the CLas-induced energetic stress. In conclusion, CLas alters the energy metabolism of its psyllid vector, D. citri, in order to secure its need for energetic nucleotides. IMPORTANCE Insect transmission of plant-pathogenic bacteria involves propagation and circulation of the bacteria within their vectors. The transmission process is complex and requires specific interactions at the molecular

  15. Bacterial extracellular polymeric substances and their effect on settlement of zoospore of Ulva fasciata.

    PubMed

    Singh, Ravindra Pal; Shukla, Mahendra K; Mishra, Avinash; Reddy, C R K; Jha, Bhavanath

    2013-03-01

    The extracellular polymeric substances (EPSs) secreted by Bacillus flexus (GU592213) were estimated to have the molecular weight of approximately 1528 and 33,686 kDa with the elemental composition of Na, P, Mg, C, O, Cl and S. The (1)H NMR and FT-IR analysis of EPS confirmed the presence of different aliphatic and aromatic groups. The EPS was amorphous in nature with an average particle size of 13.969 μm (d 0.5) and roughness of 193 nm. The GC-MS analysis has revealed different monosaccharides such as fucose, ribose, xylose, galactose, mannose and glucose. Oligo and polysaccharides were detected with MALDI TOF-TOF MS. The bacterial EPS for the first time tested as a natural substratum for settle of zoospores of Ulva fasciata by incubating for various durations ranging from 2h to 48 h. The zoospore settlement on EPS coated cover slips progressively increased with incubation time in axenic cultures over controls. The EPS, thus investigated in this study was found to facilitate the primary settlement of spores that play crucial role in recruitment of macroalgal communities in coastal environment including intertidal regions. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. Bacteriophage-encoded bacterial virulence factors and phage-pathogenicity island interactions.

    PubMed

    Boyd, E Fidelma

    2012-01-01

    The role of bacteriophages as natural vectors for some of the most potent bacterial toxins is well recognized and includes classical type I membrane-acting superantigens, type II pore-forming lysins, and type III exotoxins, such as diphtheria and botulinum toxins. Among Gram-negative pathogens, a novel class of bacterial virulence factors called effector proteins (EPs) are phage encoded among pathovars of Escherichia coli, Shigella spp., and Salmonella enterica. This chapter gives an overview of the different types of virulence factors encoded within phage genomes based on their role in bacterial pathogenesis. It also discusses phage-pathogenicity island interactions uncovered from studies of phage-encoded EPs. A detailed examination of the filamentous phage CTXφ that encodes cholera toxin is given as the sole example to date of a single-stranded DNA phage that encodes a bacterial toxin.

  17. Trogocytosis-associated cell to cell spread of intracellular bacterial pathogens.

    PubMed

    Steele, Shaun; Radlinski, Lauren; Taft-Benz, Sharon; Brunton, Jason; Kawula, Thomas H

    2016-01-23

    Macrophages are myeloid-derived phagocytic cells and one of the first immune cell types to respond to microbial infections. However, a number of bacterial pathogens are resistant to the antimicrobial activities of macrophages and can grow within these cells. Macrophages have other immune surveillance roles including the acquisition of cytosolic components from multiple types of cells. We hypothesized that intracellular pathogens that can replicate within macrophages could also exploit cytosolic transfer to facilitate bacterial spread. We found that viable Francisella tularensis, as well as Salmonella enterica bacteria transferred from infected cells to uninfected macrophages along with other cytosolic material through a transient, contact dependent mechanism. Bacterial transfer occurred when the host cells exchanged plasma membrane proteins and cytosol via a trogocytosis related process leaving both donor and recipient cells intact and viable. Trogocytosis was strongly associated with infection in mice, suggesting that direct bacterial transfer occurs by this process in vivo.

  18. O Antigen Modulates Insect Vector Acquisition of the Bacterial Plant Pathogen Xylella fastidiosa

    PubMed Central

    Rapicavoli, Jeannette N.; Kinsinger, Nichola; Perring, Thomas M.; Backus, Elaine A.; Shugart, Holly J.; Walker, Sharon

    2015-01-01

    Hemipteran insect vectors transmit the majority of plant pathogens. Acquisition of pathogenic bacteria by these piercing/sucking insects requires intimate associations between the bacterial cells and insect surfaces. Lipopolysaccharide (LPS) is the predominant macromolecule displayed on the cell surface of Gram-negative bacteria and thus mediates bacterial interactions with the environment and potential hosts. We hypothesized that bacterial cell surface properties mediated by LPS would be important in modulating vector-pathogen interactions required for acquisition of the bacterial plant pathogen Xylella fastidiosa, the causative agent of Pierce's disease of grapevines. Utilizing a mutant that produces truncated O antigen (the terminal portion of the LPS molecule), we present results that link this LPS structural alteration to a significant decrease in the attachment of X. fastidiosa to blue-green sharpshooter foreguts. Scanning electron microscopy confirmed that this defect in initial attachment compromised subsequent biofilm formation within vector foreguts, thus impairing pathogen acquisition. We also establish a relationship between O antigen truncation and significant changes in the physiochemical properties of the cell, which in turn affect the dynamics of X. fastidiosa adhesion to the vector foregut. Lastly, we couple measurements of the physiochemical properties of the cell with hydrodynamic fluid shear rates to produce a Comsol model that predicts primary areas of bacterial colonization within blue-green sharpshooter foreguts, and we present experimental data that support the model. These results demonstrate that, in addition to reported protein adhesin-ligand interactions, O antigen is crucial for vector-pathogen interactions, specifically in the acquisition of this destructive agricultural pathogen. PMID:26386068

  19. O antigen modulates insect vector acquisition of the bacterial plant pathogen Xylella fastidiosa.

    PubMed

    Rapicavoli, Jeannette N; Kinsinger, Nichola; Perring, Thomas M; Backus, Elaine A; Shugart, Holly J; Walker, Sharon; Roper, M Caroline

    2015-12-01

    Hemipteran insect vectors transmit the majority of plant pathogens. Acquisition of pathogenic bacteria by these piercing/sucking insects requires intimate associations between the bacterial cells and insect surfaces. Lipopolysaccharide (LPS) is the predominant macromolecule displayed on the cell surface of Gram-negative bacteria and thus mediates bacterial interactions with the environment and potential hosts. We hypothesized that bacterial cell surface properties mediated by LPS would be important in modulating vector-pathogen interactions required for acquisition of the bacterial plant pathogen Xylella fastidiosa, the causative agent of Pierce's disease of grapevines. Utilizing a mutant that produces truncated O antigen (the terminal portion of the LPS molecule), we present results that link this LPS structural alteration to a significant decrease in the attachment of X. fastidiosa to blue-green sharpshooter foreguts. Scanning electron microscopy confirmed that this defect in initial attachment compromised subsequent biofilm formation within vector foreguts, thus impairing pathogen acquisition. We also establish a relationship between O antigen truncation and significant changes in the physiochemical properties of the cell, which in turn affect the dynamics of X. fastidiosa adhesion to the vector foregut. Lastly, we couple measurements of the physiochemical properties of the cell with hydrodynamic fluid shear rates to produce a Comsol model that predicts primary areas of bacterial colonization within blue-green sharpshooter foreguts, and we present experimental data that support the model. These results demonstrate that, in addition to reported protein adhesin-ligand interactions, O antigen is crucial for vector-pathogen interactions, specifically in the acquisition of this destructive agricultural pathogen.

  20. Rapid, Portable, Multiplexed Detection of Bacterial Pathogens Directly from Clinical Sample Matrices

    PubMed Central

    Phaneuf, Christopher R.; Mangadu, Betty; Piccini, Matthew E.; Singh, Anup K.; Koh, Chung-Yan

    2016-01-01

    Enteric and diarrheal diseases are a major cause of childhood illness and death in countries with developing economies. Each year, more than half of a million children under the age of five die from these diseases. We have developed a portable, microfluidic platform capable of simultaneous, multiplexed detection of several of the bacterial pathogens that cause these diseases. This platform can perform fast, sensitive immunoassays directly from relevant, complex clinical matrices such as stool without extensive sample cleanup or preparation. Using only 1 µL of sample per assay, we demonstrate simultaneous multiplexed detection of four bacterial pathogens implicated in diarrheal and enteric diseases in less than 20 min. PMID:27669320

  1. Rapid, portable, multiplexed detection of bacterial pathogens directly from clinical sample matrices

    SciTech Connect

    Phaneuf, Christopher R.; Mangadu, Betty Lou Bosano; Piccini, Matthew E.; Singh, Anup K.; Koh, Chung -Yan

    2016-09-23

    Enteric and diarrheal diseases are a major cause of childhood illness and death in countries with developing economies. Each year, more than half of a million children under the age of five die from these diseases. We have developed a portable, microfluidic platform capable of simultaneous, multiplexed detection of several of the bacterial pathogens that cause these diseases. Furthermore, this platform can perform fast, sensitive immunoassays directly from relevant, complex clinical matrices such as stool without extensive sample cleanup or preparation. Using only 1 µL of sample per assay, we demonstrate simultaneous multiplexed detection of four bacterial pathogens implicated in diarrheal and enteric diseases in less than 20 min.

  2. The Role of Copper and Zinc Toxicity in Innate Immune Defense against Bacterial Pathogens*

    PubMed Central

    Djoko, Karrera Y.; Ong, Cheryl-lynn Y.; Walker, Mark J.; McEwan, Alastair G.

    2015-01-01

    Zinc (Zn) and copper (Cu) are essential for optimal innate immune function, and nutritional deficiency in either metal leads to increased susceptibility to bacterial infection. Recently, the decreased survival of bacterial pathogens with impaired Cu and/or Zn detoxification systems in phagocytes and animal models of infection has been reported. Consequently, a model has emerged in which the host utilizes Cu and/or Zn intoxication to reduce the intracellular survival of pathogens. This review describes and assesses the potential role for Cu and Zn intoxication in innate immune function and their direct bactericidal function. PMID:26055706

  3. The Role of Copper and Zinc Toxicity in Innate Immune Defense against Bacterial Pathogens.

    PubMed

    Djoko, Karrera Y; Ong, Cheryl-lynn Y; Walker, Mark J; McEwan, Alastair G

    2015-07-31

    Zinc (Zn) and copper (Cu) are essential for optimal innate immune function, and nutritional deficiency in either metal leads to increased susceptibility to bacterial infection. Recently, the decreased survival of bacterial pathogens with impaired Cu and/or Zn detoxification systems in phagocytes and animal models of infection has been reported. Consequently, a model has emerged in which the host utilizes Cu and/or Zn intoxication to reduce the intracellular survival of pathogens. This review describes and assesses the potential role for Cu and Zn intoxication in innate immune function and their direct bactericidal function.

  4. The Use of Laser-Induced Breakdown Spectroscopy for Distinguishing Between Bacterial Pathogen Species and Strains

    PubMed Central

    Multari, Rosalie A.; Cremers, David A.; Dupre, Joanne M.; Gustafson, John E.

    2013-01-01

    Laser-induced breakdown spectroscopy (LIBS) was used in a blind study to successfully differentiate bacterial pathogens, both species and strain. The pathogens used for the study were chosen and prepared by one set of researchers. The LIBS data were collected and analyzed by another set of researchers. The latter researchers had no knowledge of the sample identities other than that (1) the first five of fifteen samples were unique (not replicates) and (2) the remaining ten samples consisted of two replicates of each of the first five samples. Using only chemometric analysis of the LIBS data, the ten replicate bacterial samples were successfully matched to each of the first five samples. The results of this blind study show it is possible to differentiate the bacterial pathogens Escherichia coli, three clonal methicillin-resistant Staphylococcus aureus (MRSA) strains, and one unrelated MRSA strain using LIBS. This is an important finding because it demonstrates that LIBS can be used to determine bacterial pathogen species within a defined sample set and can be used to differentiate between clonal relationships among strains of a single multiple-antibiotic-resistant bacterial species. Such a capability is important for the development of LIBS instruments for use in medical, water, and food safety applications. PMID:20615288

  5. Bacteriophage resistance mechanisms in the fish pathogen Flavobacterium psychrophilum: linking genomic mutations to changes in bacterial virulence factors.

    PubMed

    Castillo, Daniel; Christiansen, Rói Hammershaimb; Dalsgaard, Inger; Madsen, Lone; Middelboe, Mathias

    2015-02-01

    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 resistance and the genetic modifications were supported by direct measurements of bacteriophage adsorption rates, biofilm formation, and secretion of extracellular enzymes, which were all impaired in the resistant strains, probably due to superficial structural changes. The clustered regularly interspaced short palindromic repeat (CRISPR) region was unaffected in the resistant isolates and thus did not play a role as a resistance mechanism for F. psychrophilum under the current conditions. All together, the results suggest that resistance in F. psychrophilum was driven by spontaneous mutations, which were associated with a number of derived effects on the physiological properties of the pathogen, including reduced virulence under in vitro conditions. Consequently, phage-driven physiological changes associated with resistance may have implications for the impact of the pathogen in aquaculture, and these effects of phage resistance on host properties are therefore important for the ongoing exploration of phage-based control of F. psychrophilum.

  6. Phages and the Evolution of Bacterial Pathogens: from Genomic Rearrangements to Lysogenic Conversion

    PubMed Central

    Brüssow, Harald; Canchaya, Carlos; Hardt, Wolf-Dietrich

    2004-01-01

    Comparative genomics demonstrated that the chromosomes from bacteria and their viruses (bacteriophages) are coevolving. This process is most evident for bacterial pathogens where the majority contain prophages or phage remnants integrated into the bacterial DNA. Many prophages from bacterial pathogens encode virulence factors. Two situations can be distinguished: Vibrio cholerae, Shiga toxin-producing Escherichia coli, Corynebacterium diphtheriae, and Clostridium botulinum depend on a specific prophage-encoded toxin for causing a specific disease, whereas Staphylococcus aureus, Streptococcus pyogenes, and Salmonella enterica serovar Typhimurium harbor a multitude of prophages and each phage-encoded virulence or fitness factor makes an incremental contribution to the fitness of the lysogen. These prophages behave like “swarms” of related prophages. Prophage diversification seems to be fueled by the frequent transfer of phage material by recombination with superinfecting phages, resident prophages, or occasional acquisition of other mobile DNA elements or bacterial chromosomal genes. Prophages also contribute to the diversification of the bacterial genome architecture. In many cases, they actually represent a large fraction of the strain-specific DNA sequences. In addition, they can serve as anchoring points for genome inversions. The current review presents the available genomics and biological data on prophages from bacterial pathogens in an evolutionary framework. PMID:15353570

  7. Phages and the evolution of bacterial pathogens: from genomic rearrangements to lysogenic conversion.

    PubMed

    Brüssow, Harald; Canchaya, Carlos; Hardt, Wolf-Dietrich

    2004-09-01

    Comparative genomics demonstrated that the chromosomes from bacteria and their viruses (bacteriophages) are coevolving. This process is most evident for bacterial pathogens where the majority contain prophages or phage remnants integrated into the bacterial DNA. Many prophages from bacterial pathogens encode virulence factors. Two situations can be distinguished: Vibrio cholerae, Shiga toxin-producing Escherichia coli, Corynebacterium diphtheriae, and Clostridium botulinum depend on a specific prophage-encoded toxin for causing a specific disease, whereas Staphylococcus aureus, Streptococcus pyogenes, and Salmonella enterica serovar Typhimurium harbor a multitude of prophages and each phage-encoded virulence or fitness factor makes an incremental contribution to the fitness of the lysogen. These prophages behave like "swarms" of related prophages. Prophage diversification seems to be fueled by the frequent transfer of phage material by recombination with superinfecting phages, resident prophages, or occasional acquisition of other mobile DNA elements or bacterial chromosomal genes. Prophages also contribute to the diversification of the bacterial genome architecture. In many cases, they actually represent a large fraction of the strain-specific DNA sequences. In addition, they can serve as anchoring points for genome inversions. The current review presents the available genomics and biological data on prophages from bacterial pathogens in an evolutionary framework.

  8. Evaluation of PCR Based Assays for the Improvement of Proportion Estimation of Bacterial and Viral Pathogens in Diarrheal Surveillance

    PubMed Central

    Guan, Hongxia; Zhang, Jingyun; Xiao, Yong; Sha, Dan; Ling, Xia; Kan, Biao

    2016-01-01

    Diarrhea can be caused by a variety of bacterial, viral and parasitic organisms. Laboratory diagnosis is essential in the pathogen-specific burden assessment. In the pathogen spectrum monitoring in the diarrheal surveillance, culture methods are commonly used for the bacterial pathogens' detection whereas nucleic acid based amplification, the non-cultural methods are used for the viral pathogens. Different methodology may cause the inaccurate pathogen spectrum for the bacterial pathogens because of their different culture abilities with the different media, and for the comparison of bacterial vs. viral pathogens. The application of nucleic acid-based methods in the detection of viral and bacterial pathogens will likely increase the number of confirmed positive diagnoses, and will be comparable since all pathogens will be detected based on the same nucleic acid extracts from the same sample. In this study, bacterial pathogens, including diarrheagenic Escherichia coli (DEC), Salmonella spp., Shigella spp., Vibrio parahaemolyticus and V. cholerae, were detected in 334 diarrheal samples by PCR-based methods using nucleic acid extracted from stool samples and associated enrichment cultures. A protocol was established to facilitate the consistent identification of bacterial pathogens in diarrheal patients. Five common enteric viruses were also detected by RT-PCR, including rotavirus, sapovirus, norovirus (I and II), human astrovirus, and enteric adenovirus. Higher positive rates were found for the bacterial pathogens, showing the lower proportion estimation if only using culture methods. This application will improve the quality of bacterial diarrheagenic pathogen survey, providing more accurate information pertaining to the pathogen spectrum associated with finding of food safety problems and disease burden evaluation. PMID:27065958

  9. Detection of a pathogen shift among the pectolytic bacterial pathogens of potato in Washington State

    USDA-ARS?s Scientific Manuscript database

    Bacterial tuber soft rot, aerial stem rot and blackleg are significant diseases of potatoes in Washington State. These diseases are caused by Pectobacterium carotovorum subsp. carotovorum, Pectobacterium atrosepticum, and Dickeya chrysanthemi, all characterized by the ability to produce pectolytic ...

  10. Capture and concentration of viral and bacterial foodborne pathogens using apolipoprotein H.

    PubMed

    Almand, Erin A; Goulter, Rebecca M; Jaykus, Lee-Ann

    2016-09-01

    The need for improved pathogen separation and concentration methods to reduce time-to-detection for foodborne pathogens is well recognized. Apolipoprotein H (ApoH) is an acute phase human plasma protein that has been previously shown to interact with viruses, lipopolysaccharides (LPS) and bacterial proteins. The purpose of this study was to determine if ApoH was capable of binding and efficiently capturing two representative human norovirus strains (GI.1 and GII.4), a cultivable surrogate, and four bacterial pathogens (Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica serovar Enteritidis, and Staphylococcus aureus). Experiments were carried out using an ApoH-conjugated magnetic bead-based capture followed by pathogen detection using nucleic acid amplification. For all three viruses studied, >10% capture efficiency (<1 Log10 loss in RT-qPCR amplifiable units) was observed. The same capture efficiencies were observed for the bacterial pathogens tested, with the exception of E. coli O157:H7 (approximately 1% capture efficiency, or 2 Log10 loss in CFU equivalents). The efficiency of the capture steps did not vary as a consequence of input target concentration or in the presence of an abundance of background microflora. A complementary plate-based capture assay showed that ApoH bound to a variety of human norovirus virus-like particles. ApoH has the potential to be a broadly reactive ligand for separating and concentrating representative foodborne pathogens, both bacteria and viruses. Published by Elsevier B.V.

  11. Photodynamic therapy induces an immune response against a bacterial pathogen

    PubMed Central

    Huang, Ying-Ying; Tanaka, Masamitsu; Vecchio, Daniela; Garcia-Diaz, Maria; Chang, Julie; Morimoto, Yuji; Hamblin, Michael R

    2012-01-01

    Photodynamic therapy (PDT) employs the triple combination of photosensitizers, visible light and ambient oxygen. When PDT is used for cancer, it has been observed that both arms of the host immune system (innate and adaptive) are activated. When PDT is used for infectious disease, however, it has been assumed that the direct antimicrobial PDT effect dominates. Murine arthritis caused by methicillin-resistant Staphylococcus aureus in the knee failed to respond to PDT with intravenously injected Photofrin®. PDT with intra-articular Photofrin produced a biphasic dose response that killed bacteria without destroying host neutrophils. Methylene blue was the optimum photosensitizer to kill bacteria while preserving neutrophils. We used bioluminescence imaging to noninvasively monitor murine bacterial arthritis and found that PDT with intra-articular methylene blue was not only effective, but when used before infection, could protect the mice against a subsequent bacterial challenge. The data emphasize the importance of considering the host immune response in PDT for infectious disease. PMID:22882222

  12. Black holes, antivirulence genes, and gene inactivation in the evolution of bacterial pathogens.

    PubMed

    Maurelli, Anthony T

    2007-02-01

    The evolution of bacterial pathogens from nonpathogenic ancestors is marked principally by the acquisition of virulence gene clusters on plasmids and pathogenicity islands via horizontal gene transfer. The flip side of this evolutionary force is the equally important adaptation of the newly minted pathogen to its new host niche. Pathoadaptive mutations take the form of modification of gene expression such that the pathogen is better fit to survive within the new niche. This mini-review describes the concept of pathoadaptation by loss of gene function. In this process, genes that are no longer compatible with the novel lifestyle of the pathogen are selectively inactivated either by point mutation, insertion, or deletion. These genes are called 'antivirulence genes'. Selective pressure sometimes leads to the deletion of large regions of the genome that contain antivirulence genes generating 'black holes' in the pathogen genome. Inactivation of antivirulence genes leads to a pathogen that is highly adapted to its host niche. Identification of antivirulence genes for a particular pathogen can lead to a better understanding of how it became a pathogen and the types of genetic traits that need to be silenced in order for the pathogen to colonize its new host niche successfully.

  13. Analysis of bacterial communities and bacterial pathogens in a biogas plant by the combination of ethidium monoazide, PCR and Ion Torrent sequencing.

    PubMed

    Luo, Gang; Angelidaki, Irini

    2014-09-01

    The present study investigated the changes of bacterial community composition including bacterial pathogens along a biogas plant, i.e. from the influent, to the biogas reactor and to the post-digester. The effects of post-digestion temperature and time on the changes of bacterial community composition and bacterial pathogens were also studied. Microbial analysis was made by Ion Torrent sequencing of the PCR amplicons from ethidium monoazide treated samples, and ethidium monoazide was used to cleave DNA from dead cells and exclude it from PCR amplification. Both similarity and taxonomic analysis showed that the bacterial community composition in the influent was changed after anaerobic digestion. Firmicutes were dominant in all the samples, while Proteobacteria decreased in the biogas reactor compared with the influent. Variations of bacterial community composition in the biogas reactor with time were also observed. This could be attributed to varying composition of the influent. Batch experiments showed that the methane recovery from the digested residues (obtained from biogas reactor) was mainly related with post-digestion temperature. However, post-digestion time rather than temperature had a significant effect on the changes of bacterial community composition. The changes of bacterial community composition were also reflected in the changes of relative abundance of bacterial pathogens. The richness and relative abundance of bacterial pathogens were reduced after anaerobic digestion in the biogas reactor. It was found in batch experiments that bacterial pathogens showed the highest relative abundance and richness after 30 days' post-digestion. Streptococcus bovis was found in all the samples. Our results showed that special attention should be paid to the post-digestion since the increase in relative abundance of bacterial pathogens after post-digestion might reflect regrowth of bacterial pathogens and limit biosolids disposal vectors. Copyright © 2014 Elsevier

  14. Rapid Accurate Identification of Bacterial and Viral Pathogens

    SciTech Connect

    Dunn, John

    2007-03-09

    The goals of this program were to develop two assays for rapid, accurate identification of pathogenic organisms at the strain level. The first assay "Quantitative Genome Profiling or QGP" is a real time PCR assay with a restriction enzyme-based component. Its underlying concept is that certain enzymes should cleave genomic DNA at many sites and that in some cases these cuts will interrupt the connection on the genomic DNA between flanking PCR primer pairs thereby eliminating selected PCR amplifications. When this occurs the appearance of the real-time PCR threshold (Ct) signal during DNA amplification is totally eliminated or, if cutting is incomplete, greatly delayed compared to an uncut control. This temporal difference in appearance of the Ct signal relative to undigested control DNA provides a rapid, high-throughput approach for DNA-based identification of different but closely related pathogens depending upon the nucleotide sequence of the target region. The second assay we developed uses the nucleotide sequence of pairs of shmi identifier tags (-21 bp) to identify DNA molecules. Subtle differences in linked tag pair combinations can also be used to distinguish between closely related isolates..

  15. Chemical Biology Applied to the Study of Bacterial Pathogens

    PubMed Central

    Anthouard, Rebecca

    2014-01-01

    In recent years, chemical biology and chemical genomics have been increasingly applied to the field of microbiology to uncover new potential therapeutics as well as to probe virulence mechanisms in pathogens. The approach offers some clear advantages, as identified compounds (i) can serve as a proof of principle for the applicability of drugs to specific targets; (ii) can serve as conditional effectors to explore the function of their targets in vitro and in vivo; (iii) can be used to modulate gene expression in otherwise genetically intractable organisms; and (iv) can be tailored to a narrow or broad range of bacteria. This review highlights recent examples from the literature to illustrate how the use of small molecules has advanced discovery of novel potential treatments and has been applied to explore biological mechanisms underlying pathogenicity. We also use these examples to discuss practical considerations that are key to establishing a screening or discovery program. Finally, we discuss the advantages and challenges of different approaches and the methods that are emerging to address these challenges. PMID:25404026

  16. Direct detection of bacterial pathogens in representative dairy products using a combined bacterial concentration-PCR approach.

    PubMed

    Stevens, K A; Jaykus, L-A

    2004-01-01

    To develop a simple, rapid method to concentrate and purify bacteria and their nucleic acids from complex dairy food matrices in preparation for direct pathogen detection using polymerase chain reaction (PCR). Plain non-fat yogurt and cheddar cheese were each seeded with Listeria monocytogenes or Salmonella enterica serovar. Enteritidis in the range of 10(1)-10(6) CFU per 11-g sample. Samples were then processed for bacterial concentration using high-speed centrifugation (9700 g) followed by DNA extraction, PCR amplification, and amplicon confirmation by hybridization. Bacterial recoveries after centrifugation ranged from 53 to >100% and 71 to >100% for serovar. Enteritidis and L. monocytogenes, respectively, in the non-fat yogurt samples; and from 77 to >100% and 69 to >100% for serovar. Enteritidis and L. monocytogenes, respectively, in the cheddar cheese samples. There were no significant differences in recovery efficiency at different inocula levels, and losses to discarded supernatants were always <5%, regardless of dairy product or pathogen. When followed by pathogen detection using PCR and confirmation by amplicon hybridization, detection limits of 10(3) and 10(1) CFU per 11-g sample were achieved for L. monocytogenes and serovar. Enteritidis, respectively, in both product types and without prior cultural enrichment. This study represents progress toward the rapid and efficient direct detection of pathogens from complex food matrices at detection limits approaching those that might be anticipated in naturally contaminated products.

  17. Prevalence of gastrointestinal bacterial pathogens in a population of zoo animals.

    PubMed

    Stirling, J; Griffith, M; Blair, I; Cormican, M; Dooley, J S G; Goldsmith, C E; Glover, S G; Loughrey, A; Lowery, C J; Matsuda, M; McClurg, R; McCorry, K; McDowell, D; McMahon, A; Cherie Millar, B; Nagano, Y; Rao, J R; Rooney, P J; Smyth, M; Snelling, W J; Xu, J; Moore, J E

    2008-04-01

    Faecal prevalence of gastrointestinal bacterial pathogens, including Campylobacter, Escherichia coli O157:H7, Salmonella, Shigella, Yersinia, as well as Arcobacter, were examined in 317 faecal specimens from 44 animal species in Belfast Zoological Gardens, during July-September 2006. Thermophilic campylobacters including Campylobacter jejuni, Campylobacter coli and Campylobacter lari, were the most frequently isolated pathogens, where members of this genus were isolated from 11 animal species (11 of 44; 25%). Yersinia spp. were isolated from seven animal species (seven of 44; 15.9%) and included, Yersinia enterocolitica (five of seven isolates; 71.4%) and one isolate each of Yersinia frederiksenii and Yersinia kristensenii. Only one isolate of Salmonella was obtained throughout the entire study, which was an isolate of Salmonella dublin (O 1,9,12: H g, p), originating from tiger faeces after enrichment. None of the animal species found in public contact areas of the zoo were positive for any gastrointestinal bacterial pathogens. Also, water from the lake in the centre of the grounds, was examined for the same bacterial pathogens and was found to contain C. jejuni. This study is the first report on the isolation of a number of important bacterial pathogens from a variety of novel host species, C. jejuni from the red kangaroo (Macropus rufus), C. lari from a maned wolf (Chrysocyon brachyurus), Y. kristensenii from a vicugna (Vicugna vicugna) and Y. enterocolitica from a maned wolf and red panda (Ailurus fulgens). In conclusion, this study demonstrated that the faeces of animals in public contact areas of the zoo were not positive for the bacterial gastrointestinal pathogens examined. This is reassuring for the public health of visitors, particularly children, who enjoy this educational and recreational resource.

  18. Bacterial proteases from the intracellular vacuole niche; protease conservation and adaptation for pathogenic advantage.

    PubMed

    Huston, Wilhelmina M

    2010-06-01

    Proteases with important roles for bacterial pathogens that specifically reside within intracellular vacuoles are frequently homologous to those that have important virulence functions for other bacteria. Research has identified that some of these conserved proteases have evolved specialized functions for intracellular vacuole-residing bacteria. Unique proteases with pathogenic functions have also been described from Chlamydia, Mycobacteria, and Legionella. These findings suggest that there are further novel functions for proteases from these bacteria that remain to be described. This review summarizes the recent findings of novel protease functions from the intracellular human pathogenic bacteria that reside exclusively in vacuoles.

  19. Next generation sequencing uncovers unexpected bacterial pathogens in ticks in western Europe.

    PubMed

    Vayssier-Taussat, Muriel; Moutailler, Sara; Michelet, Lorraine; Devillers, Elodie; Bonnet, Sarah; Cheval, Justine; Hébert, Charles; Eloit, Marc

    2013-01-01

    Ticks are highly susceptible to global environmental and socio-economical changes. Several tick-borne pathogens have been reported in new geographical regions while new species, strains or genetic variants of tick-borne microorganisms are continually being detected. However, tick-borne pathogens are still poorly understood, and it is estimated that half of all human tick-borne disease has an unknown origin. Therefore in order to prevent these diseases, more effort is required to identify unknown or unexpected tick-borne pathogens. Ixodes ricinus is the vector for a broad range of bacterial pathogens and the most prevalent tick in Europe. The aim of the present study was to evaluate the capability of Next Generation Sequencing (NGS) to extend the inventory of pathogenic bacteria carried by this species of tick in France. RNA and DNA were extracted from 1450 I. ricinus questing nymphs collected by flagging in Alsace, France. RNA was pooled and used for NGS. Following de novo assembly, bacterial contigs were assigned to the closest known taxonomy. DNA was used for real time PCR to confirm taxonomic species assignment of NGS-derived contigs for the doubtful cases, and for determination of prevalence. We have generated a global in-depth picture of tick-borne bacteria. We identified RNA from the main pathogenic bacterial species known to be transmitted by I. ricinus. In addition we also identified unanticipated bacterial species for which we have estimated the prevalence within those ticks inhabiting the studied areas. The data obtained from this study has proven that NGS has an enormous potential to detect the unexpected and provides the means to monitor pathogen occurrence.

  20. Etiology of Appendicitis in Children: The Role of Bacterial and Viral Pathogens.

    PubMed

    Richardsen, I; Schöb, D S; Ulmer, T F; Steinau, G; Neumann, U P; Klink, C D; Lambertz, A

    2016-01-01

    Although acute appendicitis is the most common cause for abdominal surgery in children, its etiology is still largely unknown. The aim of this study was to evaluate the role of bacterial and viral pathogens for the etiology of appendicitis in children. Between 2000 and 2010, 277 children underwent appendectomy in our institution. On this collective, a retrospective study was performed on to identify the presence of bacterial or viral pathogens. Intraoperatively, 39% of cases showed acute, 9% of cases chronic, and 41% of cases ulcerous inflammation. Bowel perforation was found in 7% of cases and four percent of the children had no inflammation of the appendix at all. Escherichia coli was the predominant bacterium with an incidence of 27.4%, followed by streptococci (9.8%). Concerning viral pathogens, adenovirus was the most common with an incidence of 5.4% followed by rotavirus (4.7%). Significant correlations between histopathological findings and present pathogens were found: in cases of bowel perforation there were significantly more infections with E. coli bacteria (32.2%, p < .001), streptococci (12.2%, p < 0.001), and Pseudomonas aeruginosa (6.7%, p < .001) whereas chronic inflammations were accompanied with a significantly elevated rate of yersinia infections (2.5%, p = .016). Acute inflammations were significantly more often associated with campylobacter (1.7%, p = .011) and oxyures infections (6.1%, p < .001). In relation to the patients' age, a significant accumulation of different pathogens was observed. CRP- and leukocyte counts showed differences between viral and bacterial inflammations. Our data indicates that appendicitis in children might be triggered by bacterial and viral pathogens and that the type of pathogen directly correlates with patient age, type of inflammation, and level of inflammation values. To confirm and further evaluate these findings, additional studies need to be conducted.

  1. Modulation of connexin signaling by bacterial pathogens and their toxins.

    PubMed

    Ceelen, Liesbeth; Haesebrouck, Freddy; Vanhaecke, Tamara; Rogiers, Vera; Vinken, Mathieu

    2011-09-01

    Inherent to their pivotal tasks in the maintenance of cellular homeostasis, gap junctions, connexin hemichannels, and pannexin hemichannels are frequently involved in the dysregulation of this critical balance. The present paper specifically focuses on their roles in bacterial infection and disease. In particular, the reported biological outcome of clinically important bacteria including Escherichia coli, Shigella flexneri, Yersinia enterocolitica, Helicobacter pylori, Bordetella pertussis, Aggregatibacter actinomycetemcomitans, Pseudomonas aeruginosa, Citrobacter rodentium, Clostridium species, Streptococcus pneumoniae, and Staphylococcus aureus and their toxic products on connexin- and pannexin-related signaling in host cells is reviewed. Particular attention is paid to the underlying molecular mechanisms of these effects as well as to the actual biological relevance of these findings.

  2. Neutrophils Discriminate between Lipopolysaccharides of Different Bacterial Sources and Selectively Release Neutrophil Extracellular Traps

    PubMed Central

    Pieterse, Elmar; Rother, Nils; Yanginlar, Cansu; Hilbrands, Luuk B.; van der Vlag, Johan

    2016-01-01

    The release of neutrophil extracellular traps (NETs), either during “suicidal” or “vital” NETosis, represents an important strategy of neutrophils to combat Gram-negative bacteria. Lipopolysaccharide (LPS), a major component of the outer membrane of Gram-negative bacteria, is a reported stimulus for NET formation. Although it is widely acknowledged that the structural diversity in LPS structures can elicit heterogeneous immune responses, species- and serotype-specific differences in the capacity of LPS to trigger NET formation have not yet been investigated. In the present study, we compared the NET-inducing potential of LPS derived from Escherichia coli (serotypes O55:B5, O127:B8, O128:B12, O111:B4, and O26:B6), Salmonella enterica (serotype enteritidis), and Pseudomonas aeruginosa (serotype 10), under platelet-free and platelet-rich conditions in vitro, and in whole blood ex vivo. Here, we demonstrate that under serum- and platelet-free conditions, mimicking tissue circumstances, neutrophils discriminate between LPS of different bacterial sources and selectively release NETs only in response to LPS derived from E. coli O128:B12 and P. aeruginosa 10, which both induced “suicidal” NETosis in an autophagy- and reactive oxygen species (ROS)-dependent, but TLR4-independent manner. Intriguingly, in whole blood cultures ex vivo, or in vitro in the presence of platelets, all LPS serotypes induced “vital” NET formation. This platelet-dependent release of NETs occurred rapidly without neutrophil cell death and was independent from ROS formation and autophagy but required platelet TLR4 and CD62P-dependent platelet–neutrophil interactions. Taken together, our data reveal a complex interplay between neutrophils and LPS, which can induce both “suicidal” and “vital” NETosis, depending on the bacterial origin of LPS and the presence or absence of platelets. Our findings suggest that LPS sensing by neutrophils may be a critical determinant for

  3. Within-Host Envelope Remodelling and its Impact in Bacterial Pathogen Recognition.

    PubMed

    Pucciarelli, M Graciela; García-Del Portillo, Francisco

    2017-09-06

    Following colonization of host tissues, bacterial pathogens encounter new niches in which they must gain access to nutrients and cope with stresses and defence signals generated by the host. For some pathogens, the adaptation to a new 'within-host' lifestyle involves modifications of envelope components that bear molecular patterns normally recognized by the host innate immune system. These new modified patterns limit host recognition, therefore promoting immune evasion and pathogenicity. In this review, we describe how envelope components like the peptidoglycan or lipopolysaccharide can be altered within the host to impair responses triggered by pattern recognition receptors (PRR). We also discuss the few cases reported to date of chemical modifications that occur in the envelope of some intracellular bacterial pathogens when they reside inside eukaryotic cells. These envelope alterations may have evolved due to the sentinel role performed by PRRs over pathogen-specific molecular patterns. The available data indicate that only selected pathogens seem to evade recognition due to 'within-host' envelope changes, with most of them displaying such patterns also in non host environments. Given the importance of these alterations, future studies should focus in the responsible pathogen regulators, most yet unknown, that could be targeted to prevent immune evasion.

  4. Water relations in the interaction of foliar bacterial pathogens with plants.

    PubMed

    Beattie, Gwyn A

    2011-01-01

    This review examines the many ways in which water influences the relations between foliar bacterial pathogens and plants. As a limited resource in aerial plant tissues, water is subject to manipulation by both plants and pathogens. A model is emerging that suggests that plants actively promote localized desiccation at the infection site and thus restrict pathogen growth as one component of defense. Similarly, many foliar pathogens manipulate water relations as one component of pathogenesis. Nonvascular pathogens do this using effectors and other molecules to alter hormonal responses and enhance intercellular watersoaking, whereas vascular pathogens use many mechanisms to cause wilt. Because of water limitations on phyllosphere surfaces, bacterial colonists, including pathogens, benefit from the protective effects of cellular aggregation, synthesis of hygroscopic polymers, and uptake and production of osmoprotective compounds. Moreover, these bacteria employ tactics for scavenging and distributing water to overcome water-driven barriers to nutrient acquisition, movement, and signal exchange on plant surfaces. Copyright © 2011 by Annual Reviews. All rights reserved.

  5. A Review Approaches to Identify Enteric Bacterial Pathogens

    PubMed Central

    Amani, Jafar; Mirhosseini, Seyed Ali; Imani Fooladi, Abbas Ali

    2014-01-01

    Context: Diarrhea is a common disease across the world. According to WHO, every year about two billion cases of diarrhea are reported in the world. It occurs mainly in the tropical regions and is a main cause of morbidity and mortality, particularly in young children and adults. Evidence Acquisition: One of the major causes of diarrheal diseases is bacteria; detection of pathogenic bacteria is a global key to the prevention and identification of food-borne diseases and enteric infections (like diarrhea). Conclusions: Therefore, development of rapid diagnostic methods with suitable sensitivity and specificity is very important about this infectious disease. In this review, we will discuss some of the important diagnostic methods. PMID:25793091

  6. Effect of pH, salt and chemical rinses on bacterial attachment to extracellular matrix proteins.

    PubMed

    Zulfakar, Siti Shahara; White, Jason D; Ross, Tom; Tamplin, Mark

    2013-06-01

    Microbial contamination of carcass surfaces occurs during slaughter and post-slaughter processing steps, therefore interventions are needed to enhance meat safety and quality. Although many studies have been done at the macro-level, little is known about specific processes that influence bacterial attachment to carcass surfaces, particularly the role of extracellular matrix (ECM) proteins. In the present study, the effect of pH and salt (NaCl, KCl and CaCl2) on attachment of Escherichia coli and Salmonella isolates to dominant ECM proteins: collagen I, fibronectin, collagen IV and laminin were assessed. Also, the effects of three chemical rinses commonly used in abattoirs (2% acetic acid, 2% lactic acid and 10% trisodium phosphate (TSP)) were tested. Within a pH range of 5-9, there was no significant effect on attachment to ECM proteins, whereas the effect of salt type and concentration varied depending on combination of strain and ECM protein. A concentration-dependant effect was observed with NaCl and KCl (0.1-0.85%) on attachment of E. coli M23Sr, but only to collagen I. One-tenth percent CaCl2 produced the highest level of attachment to ECM proteins for E. coli M23Sr and EC614. In contrast, higher concentrations of CaCl2 increased attachment of E. coli EC473 to collagen IV. Rinses containing TSP produced >95% reduction in attachment to all ECM proteins. These observations will assist in the design of targeted interventions to prevent or disrupt contamination of meat surfaces, thus improving meat safety and quality. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. Multiplex PCR assay for simultaneous detection of six major bacterial pathogens of rice.

    PubMed

    Cui, Z; Ojaghian, M R; Tao, Z; Kakar, K U; Zeng, J; Zhao, W; Duan, Y; Vera Cruz, C M; Li, B; Zhu, B; Xie, G

    2016-05-01

    The aim of this study was to develop a multiplex PCR (mPCR) assay for rapid, sensitive and simultaneous detection of six important rice pathogens: Xanthomonas oryzae pv. oryzae, X. oryzae pv. oryzicola, Pseudomonas fuscovaginae, Burkholderia glumae, Burkholderia gladioli and Acidovorax avenae subsp. avenae. Specific primers were designed through a bioinformatics pipeline. Sensitivity of detection was established using both traditional PCR and quantitative real-time PCR on isolated DNA and on bacterial cells both in vitro and in simulated diseased seeds and the parameters were optimized for an mPCR assay. A total of 150 bacterial strains were tested for specificity. The mPCR assay accurately predicted the presence of pathogens among 44 symptomatic and asymptomatic rice seed, sheath and leaf samples. This study confirmed that this mPCR assay is a rapid, reliable and simple tool for the simultaneous detection of six important rice bacterial pathogens. This study is the first report of a method allowing simultaneous detection of six major rice pathogens. The ability to use crude extracts from plants without bacterial isolation or DNA extraction enhances the value of this mPCR technology for rapid detection and aetiological/epidemiological studies. © 2016 The Society for Applied Microbiology.

  8. Antibacterial activity of plant extracts on foodborne bacterial pathogens and food spoilage bacteria

    USDA-ARS?s Scientific Manuscript database

    Bacterial foodborne diseases are caused by consumption of foods contaminated with bacteria and/or their toxins. In this study, we evaluated antibacterial properties of twelve different extracts including turmeric, lemon and different kinds of teas against four major pathogenic foodborne bacteria inc...

  9. Spread and transmission of bacterial pathogens in experimental populations of the nematode Caenorhabditis elegans.

    PubMed

    Diaz, S Anaid; Restif, Olivier

    2014-09-01

    Caenorhabditis elegans is frequently used as a model species for the study of bacterial virulence and innate immunity. In recent years, diverse mechanisms contributing to the nematode's immune response to bacterial infection have been discovered. Yet despite growing interest in the biochemical and molecular basis of nematode-bacterium associations, many questions remain about their ecology. Although recent studies have demonstrated that free-living nematodes could act as vectors of opportunistic pathogens in soil, the extent to which worms may contribute to the persistence and spread of these bacteria has not been quantified. We conducted a series of experiments to test whether colonization of and transmission between C. elegans nematodes could enable two opportunistic pathogens (Salmonella enterica and Pseudomonas aeruginosa) to spread on agar plates occupied by Escherichia coli. We monitored the transmission of S. enterica and P. aeruginosa from single infected nematodes to their progeny and measured bacterial loads both within worms and on the plates. In particular, we analyzed three factors affecting the dynamics of bacteria: (i) initial source of the bacteria, (ii) bacterial species, and (iii) feeding behavior of the host. Results demonstrate that worms increased the spread of bacteria through shedding and transmission. Furthermore, we found that despite P. aeruginosa's relatively high transmission rate among worms, its pathogenic effects reduced the overall number of worms colonized. This study opens new avenues to understand the role of nematodes in the epidemiology and evolution of pathogenic bacteria in the environment.

  10. A Bacterial Pathogen uses Distinct Type III Secretion Systems to Alternate between Host Kingdom

    USDA-ARS?s Scientific Manuscript database

    Gram-negative bacterial pathogens of eukaryotes often secrete proteins directly into host cells via a needle-like protein channel called a ‘type III secretion system’ (T3SS). Bacteria that are adapted to either animal or plant hosts use phylogenetically distinct T3SSs for secreting proteins. Here, ...

  11. Characterization of the bacterial stem blight pathogen of alfalfa, Pseudomonas syringae pv. syringae ALF3

    USDA-ARS?s Scientific Manuscript database

    Bacterial stem blight of alfalfa occurs sporadically in the central and western U.S. Yield losses of up to 50% of the first harvest can occur with some cultivars. Developing resistant cultivars is hampered by lack of information on the pathogen and a standard test for evaluating plant germplasm. Bac...

  12. Importance of soil amendments: survival of bacterial pathogens in manure and compost used as organic fertizliers

    USDA-ARS?s Scientific Manuscript database

    Biological soil amendments (BSA’s) like manure and compost are frequently used as organic fertilizers to soils to improve its physical and chemical properties. However, BSAs have been known to be a reservoir for enteric bacterial pathogens like enterohemorrhagic E. coli, Salmonella spp, and Listeri...

  13. Chemical inhibitors of the type three secretion system: disarming bacterial pathogens.

    PubMed

    Duncan, Miles C; Linington, Roger G; Auerbuch, Victoria

    2012-11-01

    The recent and dramatic rise of antibiotic resistance among bacterial pathogens underlies the fear that standard treatments for infectious disease will soon be largely ineffective. Resistance has evolved against nearly every clinically used antibiotic, and in the near future, we may be hard-pressed to treat bacterial infections previously conquered by "magic bullet" drugs. While traditional antibiotics kill or slow bacterial growth, an important emerging strategy to combat pathogens seeks to block the ability of bacteria to harm the host by inhibiting bacterial virulence factors. One such virulence factor, the type three secretion system (T3SS), is found in over two dozen Gram-negative pathogens and functions by injecting effector proteins directly into the cytosol of host cells. Without T3SSs, many pathogenic bacteria are unable to cause disease, making the T3SS an attractive target for novel antimicrobial drugs. Interdisciplinary efforts between chemists and microbiologists have yielded several T3SS inhibitors, including the relatively well-studied salicylidene acylhydrazides. This review highlights the discovery and characterization of T3SS inhibitors in the primary literature over the past 10 years and discusses the future of these drugs as both research tools and a new class of therapeutic agents.

  14. Analysis of apple (Malus) responses to bacterial pathogens using an oligo microarray

    USDA-ARS?s Scientific Manuscript database

    Fire blight is a devastating disease of apple (Malus x domestica) caused by the bacterial pathogen Erwinia amylovora (Ea). When infiltrated into host leaves, Ea induces reactions similar to a hypersensitive response (HR). Type III (T3SS) associated effectors, especially DspA/E, are suspected to ha...

  15. A bacterial pathogen uses distinct type III secretion systems to alternate between host kingdoms

    USDA-ARS?s Scientific Manuscript database

    Plant and animal-pathogenic bacteria utilize phylogenetically distinct type III secretion systems (T3SS) that produce needle-like injectisomes or pili for the delivery of effector proteins into host cells. Pantoea stewartii subsp. stewartii (Pnss), the causative agent of Stewart’s bacterial wilt and...

  16. Rapid, electrical impedance detection of bacterial pathogens using immobilized antimicrobial peptides.

    PubMed

    Lillehoj, Peter B; Kaplan, Christopher W; He, Jian; Shi, Wenyuan; Ho, Chih-Ming

    2014-02-01

    The detection of bacterial pathogens plays an important role in many biomedical applications, including clinical diagnostics, food and water safety, and biosecurity. Most current bacterial detection technologies, however, are unsuitable for use in resource-limited settings where the highest disease burdens often exist. Thus, there is an urgent need to develop portable, user-friendly biosensors capable of rapid detection of multiple pathogens in situ. We report a microfluidic chip for multiplexed detection of bacterial cells that uses antimicrobial peptides (AMPs) with species-specific targeting and binding capabilities. The AMPs are immobilized onto an electrical impedance microsensor array and serve as biorecognition elements for bacterial cell detection. Characterization of peptide immobilization on the sensors revealed robust surface binding via cysteine-gold interactions and vertical alignment relative to the sensor surface. Samples containing Streptococcus mutans and Pseudomonas aeruginosa were loaded in the chip, and both microorganisms were detected at minimum concentrations of 10⁵ cfu/mL within 25 min. Measurements performed in a variety of solutions revealed that high-conductivity solutions produced the largest impedance values. By integrating a highly specific bacterial cell capture scheme with rapid electrical detection, this device demonstrates great potential as a next-generation, point-of-care diagnostic platform for the detection of disease-causing pathogenic agents.

  17. Shared and distinct mechanisms of iron acquisition by bacterial and fungal pathogens of humans

    PubMed Central

    Caza, Mélissa; Kronstad, James W.

    2013-01-01

    Iron is the most abundant transition metal in the human body and its bioavailability is stringently controlled. In particular, iron is tightly bound to host proteins such as transferrin to maintain homeostasis, to limit potential damage caused by iron toxicity under physiological conditions and to restrict access by pathogens. Therefore, iron acquisition during infection of a human host is a challenge that must be surmounted by every successful pathogenic microorganism. Iron is essential for bacterial and fungal physiological processes such as DNA replication, transcription, metabolism, and energy generation via respiration. Hence, pathogenic bacteria and fungi have developed sophisticated strategies to gain access to iron from host sources. Indeed, siderophore production and transport, iron acquisition from heme and host iron-containing proteins such as hemoglobin and transferrin, and reduction of ferric to ferrous iron with subsequent transport are all strategies found in bacterial and fungal pathogens of humans. This review focuses on a comparison of these strategies between bacterial and fungal pathogens in the context of virulence and the iron limitation that occurs in the human body as a mechanism of innate nutritional defense. PMID:24312900

  18. Imaging InlC Secretion to Investigate Cellular Infection by the Bacterial Pathogen Listeria monocytogenes

    PubMed Central

    Kühbacher, Andreas; Gouin, Edith; Cossart, Pascale; Pizarro-Cerdá, Javier

    2013-01-01

    Bacterial intracellular pathogens can be conceived as molecular tools to dissect cellular signaling cascades due to their capacity to exquisitely manipulate and subvert cell functions which are required for the infection of host target tissues. Among these bacterial pathogens, Listeria monocytogenes is a Gram positive microorganism that has been used as a paradigm for intracellular parasitism in the characterization of cellular immune responses, and which has played instrumental roles in the discovery of molecular pathways controlling cytoskeletal and membrane trafficking dynamics. In this article, we describe a robust microscopical assay for the detection of late cellular infection stages of L. monocytogenes based on the fluorescent labeling of InlC, a secreted bacterial protein which accumulates in the cytoplasm of infected cells; this assay can be coupled to automated high-throughput small interfering RNA screens in order to characterize cellular signaling pathways involved in the up- or down-regulation of infection. PMID:24084755

  19. Bacterial pathogens activate plasminogen to breach tissue barriers and escape from innate immunity.

    PubMed

    Peetermans, Marijke; Vanassche, Thomas; Liesenborghs, Laurens; Lijnen, Roger H; Verhamme, Peter

    2016-11-01

    Both coagulation and fibrinolysis are tightly connected with the innate immune system. Infection and inflammation cause profound alterations in the otherwise well-controlled balance between coagulation and fibrinolysis. Many pathogenic bacteria directly exploit the host's hemostatic system to increase their virulence. Here, we review the capacity of bacteria to activate plasminogen. The resulting proteolytic activity allows them to breach tissue barriers and evade innate immune defense, thus promoting bacterial spreading. Yersinia pestis, streptococci of group A, C and G and Staphylococcus aureus produce a specific bacterial plasminogen activator. Moreover, surface plasminogen receptors play an established role in pneumococcal, borrelial and group B streptococcal infections. This review summarizes the mechanisms of bacterial activation of host plasminogen and the role of the fibrinolytic system in infections caused by these pathogens.

  20. Bacterial pathogens associated with bloody diarrhea in Uruguayan children.

    PubMed

    Mota, M I; Gadea, M P; González, S; González, G; Pardo, L; Sirok, A; Rivas, M; Algorta, G; Schelotto, F; Varela, G

    2010-01-01

    Diarrheal disease continues to be a serious health problem, especially in developing countries. Bloody diarrhea represents approximately 20-30% of all cases and has higher morbidity and mortality. Treatment with antibiotics is beneficial in cases of Shigella, Campylobacter, Yersinia and Salmonella infection, principally in those children with a higher risk of invasive disease. The aims of this study were to detect the bacterial agents associated with bloody diarrhea in children and to determine their antimicrobial susceptibility patterns. Between June 2001 and January 2008, 249 children with bloody diarrhea were studied. Shigella and Shiga toxin-producing Escherichia coli (STEC) were recovered from 48 (19.3%) and 3 (1.2%) of the total of cases, respectively. In 49 out of 249 children, in whom other enteropathogens were investigated, we recovered Campylobacter jejuni from 7 children (14.3%), Salmonella spp. from 2 (4.1%) and Aeromonas spp. from 1 (2%) in addition to Shigella from 7 children (14.3%). Thirty-four (70%) Shigella isolates showed resistance to ampicillin and 13 (27%) to trimethoprim-sulfamethoxazole. All Shigella isolates were susceptible to nalidixic acid, ciprofloxacin and ceftriaxone. Salmonella and STEC isolates were susceptible to all antibiotics assayed. Thus, the use of trimethoprim-sulfamethoxazole or ampicillin would not be appropriate for the empirical treatment of Shigella - associated diarrhea.

  1. Extraction of total nucleic acids from ticks for the detection of bacterial and viral pathogens.

    PubMed

    Crowder, Chris D; Rounds, Megan A; Phillipson, Curtis A; Picuri, John M; Matthews, Heather E; Halverson, Justina; Schutzer, Steven E; Ecker, David J; Eshoo, Mark W

    2010-01-01

    Ticks harbor numerous bacterial, protozoal, and viral pathogens that can cause serious infections in humans and domestic animals. Active surveillance of the tick vector can provide insight into the frequency and distribution of important pathogens in the environment. Nucleic-acid based detection of tick-borne bacterial, protozoan, and viral pathogens requires the extraction of both DNA and RNA (total nucleic acids) from ticks. Traditional methods for nucleic acid extraction are limited to extraction of either DNA or the RNA from a sample. Here we present a simple bead-beating based protocol for extraction of DNA and RNA from a single tick and show detection of Borrelia burgdorferi and Powassan virus from individual, infected Ixodes scapularis ticks. We determined expected yields for total nucleic acids by this protocol for a variety of adult tick species. The method is applicable to a variety of arthropod vectors, including fleas and mosquitoes, and was partially automated on a liquid handling robot.

  2. Extraction of Total Nucleic Acids From Ticks for the Detection of Bacterial and Viral Pathogens

    PubMed Central

    Crowder, Chris D.; Rounds, Megan A.; Phillipson, Curtis A.; Picuri, John M.; Matthews, Heather E.; Halverson, Justina; Schutzer, Steven E.; Ecker, David J.; Eshoo, Mark W.

    2010-01-01

    Ticks harbor numerous bacterial, protozoal, and viral pathogens that can cause serious infections in humans and domestic animals. Active surveillance of the tick vector can provide insight into the frequency and distribution of important pathogens in the environment. Nucleic-acid based detection of tick-borne bacterial, protozoan, and viral pathogens requires the extraction of both DNA and RNA (total nucleic acids) from ticks. Traditional methods for nucleic acid extraction are limited to extraction of either DNA or the RNA from a sample. Here we present a simple bead-beating based protocol for extraction of DNA and RNA from a single tick and show detection of Borrelia burgdorferi and Powassan virus from individual, infected Ixodes scapularis ticks. We determined expected yields for total nucleic acids by this protocol for a variety of adult tick species. The method is applicable to a variety of arthropod vectors, including fleas and mosquitoes, and was partially automated on a liquid handling robot. PMID:20180313

  3. The role and regulation of catalase in respiratory tract opportunistic bacterial pathogens.

    PubMed

    Eason, Mia M; Fan, Xin

    2014-09-01

    Respiratory tract bacterial pathogens are the etiologic agents of a variety of illnesses. The ability of these bacteria to cause disease is imparted through survival within the host and avoidance of pathogen clearance by the immune system. Respiratory tract pathogens are continually bombarded by reactive oxygen species (ROS), which may be produced by competing bacteria, normal metabolic function, or host immunological responses. In order to survive and proliferate, bacteria have adapted defense mechanisms to circumvent the effects of ROS. Bacteria employ the use of anti-oxidant enzymes, catalases and catalase-peroxidases, to relieve the effects of the oxidative stressors to which they are continually exposed. The decomposition of ROS has been shown to provide favorable conditions in which respiratory tract opportunistic bacterial pathogens such as Haemophilus influenzae, Mycobacterium tuberculosis, Legionella pneumophila, and Neisseria meningitidis are able to withstand exposure to highly reactive molecules and yet survive. Bacteria possessing mutations in the catalase gene have a decreased survival rate, yet may be able to compensate for the lack of catalatic activity if peroxidatic activity is present. An incomplete knowledge of the mechanisms by which catalase and catalase-peroxidases are regulated still persists, however, in some bacterial species, a regulatory factor known as OxyR has been shown to either up-regulate or down-regulate catalase gene expression. Yet, more research is still needed to increase the knowledge base in relation to this enzyme class. As with this review, we focus on major respiratory tract opportunistic bacterial pathogens in order to elucidate the function and regulation of catalases. The importance of the research could lead to the development of novel treatments against respiratory bacterial infections. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Plutonium Interactions with Pseudomonas sp. and its Extracellular Polymeric Substances (Sorption and Reduction of Plutonium by Bacterial Extracellular Polymeric Substances)

    DOE PAGES

    Boggs, Mark A.; Jiao, Yongqin; Dai, Zurong; ...

    2016-09-30

    Safe and effective nuclear waste disposal, as well as accidental radionuclide releases, necessitates our understanding of the fate of radionuclides in the environment, including their interaction with microorganisms. We examined the sorption of Pu(IV) and Pu(V) toPseudomonassp. strain EPS-1W, an aerobic bacterium isolated from plutonium (Pu) contaminated groundwater collected in the United States at the Nevada National Security Site (NNSS), Nevada. We compared Pu sorption to cells with and without bound extracellular polymeric substances (EPS). Wild type cells with intact EPS sorbed Pu(V) more effectively than cells with EPS removed. In contrast, cells with and without EPS showed the samemore » sorption affinity for Pu(IV).In vitroexperiments with extracted EPS revealed rapid reduction of Pu(V) to Pu(IV). Transmission Electron Microscopy indicated that 2-3 nm nanocrystalline Pu(IV)O2formed on cells equilibrated with high concentrations of Pu(IV) but not Pu(V). Thus, EPS, while facilitating Pu(V) reduction, inhibit the formation of nanocrystalline Pu(IV) precipitates. ImportanceOur results indicate that EPS are an effective reductant for Pu(V) and sorbent for Pu(IV), and may impact Pu redox cycling and mobility in the environment. Additionally, the resulting Pu morphology associated with EPS will depend on the concentration and initial Pu oxidation state. While our results are not directly applicable to the Pu transport situation at the NNSS, the results suggest that, in general, stationary microorganisms and biofilms will tend to limit the migration of Pu and provide an important Pu retardation mechanism in the environment. In a broader sense, our results along with a growing body of literature highlight the important role of microorganisms as producers of redox-active organic ligands and therefore as modulators of radionuclide redox transformations and complexation in the subsurface.« less

  5. Human pathogens utilize host extracellular matrix proteins laminin and collagen for adhesion and invasion of the host.

    PubMed

    Singh, Birendra; Fleury, Christophe; Jalalvand, Farshid; Riesbeck, Kristian

    2012-11-01

    Laminin (Ln) and collagen are multifunctional glycoproteins that play an important role in cellular morphogenesis, cell signalling, tissue repair and cell migration. These proteins are ubiquitously present in tissues as a part of the basement membrane (BM), constitute a protective layer around blood capillaries and are included in the extracellular matrix (ECM). As a component of BMs, both Lns and collagen(s), thus function as major mechanical containment molecules that protect tissues from pathogens. Invasive pathogens breach the basal lamina and degrade ECM proteins of interstitial spaces and connective tissues using various ECM-degrading proteases or surface-bound plasminogen and matrix metalloproteinases recruited from the host. Most pathogens associated with the respiratory, gastrointestinal, or urogenital tracts, as well as with the central nervous system or the skin, have the capacity to bind and degrade Lns and collagen(s) in order to adhere to and invade host tissues. In this review, we focus on the adaptability of various pathogens to utilize these ECM proteins as enhancers for adhesion to host tissues or as a targets for degradation in order to breach the cellular barriers. The major pathogens discussed are Streptococcus, Staphylococcus, Pseudomonas, Salmonella, Yersinia, Treponema, Mycobacterium, Clostridium, Listeria, Porphyromonas and Haemophilus; Candida, Aspergillus, Pneumocystis, Cryptococcus and Coccidioides; Acanthamoeba, Trypanosoma and Trichomonas; retrovirus and papilloma virus.

  6. Bacterial-like PPP protein phosphatases: novel sequence alterations in pathogenic eukaryotes and peculiar features of bacterial sequence similarity.

    PubMed

    Kerk, David; Uhrig, R Glen; Moorhead, Greg B

    2013-01-01

    Reversible phosphorylation is a widespread modification affecting the great majority of eukaryotic cellular proteins, and whose effects influence nearly every cellular function. Protein phosphatases are increasingly recognized as exquisitely regulated contributors to these changes. The PPP (phosphoprotein phosphatase) family comprises enzymes, which catalyze dephosphorylation at serine and threonine residues. Nearly a decade ago, "bacterial-like" enzymes were recognized with similarity to proteins from various bacterial sources: SLPs (Shewanella-like phosphatases), RLPHs (Rhizobiales-like phosphatases), and ALPHs (ApaH-like phosphatases). A recent article from our laboratory appearing in Plant Physiology characterizes their extensive organismal distribution, abundance in plant species, predicted subcellular localization, motif organization, and sequence evolution. One salient observation is the distinct evolutionary trajectory followed by SLP genes and proteins in photosynthetic eukaryotes vs. animal and plant pathogens derived from photosynthetic ancestors. We present here a closer look at sequence data that emphasizes the distinctiveness of pathogen SLP proteins and that suggests that they might represent novel drug targets. A second observation in our original report was the high degree of similarity between the bacterial-like PPPs of eukaryotes and closely related proteins of the "eukaryotic-like" phyla Myxococcales and Planctomycetes. We here reflect on the possible implications of these observations and their importance for future research.

  7. Detection of bacterial pathogens including potential new species in human head lice from Mali

    PubMed Central

    Amanzougaghene, Nadia; Fenollar, Florence; Sangaré, Abdoul Karim; Sissoko, Mahamadou S.; Doumbo, Ogobara K.; Raoult, Didier

    2017-01-01

    In poor African countries, where no medical and biological facilities are available, the identification of potential emerging pathogens of concern at an early stage is challenging. Head lice, Pediculus humanus capitis, have a short life, feed only on human blood and do not transmit pathogens to their progeny. They are, therefore, a perfect tool for the xenodiagnosis of current or recent human infection. This study assessed the occurrence of bacterial pathogens from head lice collected in two rural villages from Mali, where a high frequency of head lice infestation had previously been reported, using molecular methods. Results show that all 600 head lice, collected from 117 individuals, belonged to clade E, specific to West Africa. Bartonella quintana, the causative agent of trench fever, was identified in three of the 600 (0.5%) head lice studied. Our study also shows, for the first time, the presence of the DNA of two pathogenic bacteria, namely Coxiella burnetii (5.1%) and Rickettsia aeschlimannii (0.6%), detected in human head lice, as well as the DNA of potential new species from the Anaplasma and Ehrlichia genera of unknown pathogenicity. The finding of several Malian head lice infected with B. quintana, C. burnetii, R. aeschlimannii, Anaplasma and Ehrlichia is alarming and highlights the need for active survey programs to define the public health consequences of the detection of these emerging bacterial pathogens in human head lice. PMID:28931077

  8. Development of a Selective Medium for the Fungal Pathogen Fusarium graminearum Using Toxoflavin Produced by the Bacterial Pathogen Burkholderia glumae.

    PubMed

    Jung, Boknam; Lee, Sehee; Ha, Jiran; Park, Jong-Chul; Han, Sung-Sook; Hwang, Ingyu; Lee, Yin-Won; Lee, Jungkwan

    2013-12-01

    The ascomycete fungus Fusarium graminearum is a major causal agent for Fusarium head blight in cereals and produces mycotoxins such as trichothecenes and zearalenone. Isolation of the fungal strains from air or cereals can be hampered by various other airborne fungal pathogens and saprophytic fungi. In this study, we developed a selective medium specific to F. graminearum using toxoflavin produced by the bacterial pathogen Burkholderia glumae. F. graminearum was resistant to toxoflavin, while other fungi were sensitive to this toxin. Supplementing toxoflavin into medium enhanced the isolation of F. graminearum from rice grains by suppressing the growth of saprophytic fungal species. In addition, a medium with or without toxoflavin exposed to wheat fields for 1 h had 84% or 25%, respectively, of colonies identified as F. graminearum. This selection medium provides an efficient tool for isolating F. graminearum, and can be adopted by research groups working on genetics and disease forecasting.

  9. Virulence and Pathogen Multiplication: A Serial Passage Experiment in the Hypervirulent Bacterial Insect-Pathogen Xenorhabdus nematophila

    PubMed Central

    Chapuis, Élodie; Pagès, Sylvie; Emelianoff, Vanya; Givaudan, Alain; Ferdy, Jean-Baptiste

    2011-01-01

    The trade-off hypothesis proposes that the evolution of pathogens' virulence is shaped by a link between virulence and contagiousness. This link is often assumed to come from the fact that pathogens are contagious only if they can reach high parasitic load in the infected host. In this paper we present an experimental test of the hypothesis that selection on fast replication can affect virulence. In a serial passage experiment, we selected 80 lines of the bacterial insect-pathogen Xenorhabdus nematophila to multiply fast in an artificial culture medium. This selection resulted in shortened lag phase in our selected bacteria. We then injected these bacteria into insects and observed an increase in virulence. This could be taken as a sign that virulence in Xenorhabdus is linked to fast multiplication. But we found, among the selected lineages, either no link or a positive correlation between lag duration and virulence: the most virulent bacteria were the last to start multiplying. We then surveyed phenotypes that are under the control of the flhDC super regulon, which has been shown to be involved in Xenorhabdus virulence. We found that, in one treatment, the flhDC regulon has evolved rapidly, but that the changes we observed were not connected to virulence. All together, these results indicate that virulence is, in Xenorhabdus as in many other pathogens, a multifactorial trait. Being able to grow fast is one way to be virulent. But other ways exist which renders the evolution of virulence hard to predict. PMID:21305003

  10. Bacterial Genomics Reveal the Complex Epidemiology of an Emerging Pathogen in Arctic and Boreal Ungulates

    PubMed Central

    Forde, Taya L.; Orsel, Karin; Zadoks, Ruth N.; Biek, Roman; Adams, Layne G.; Checkley, Sylvia L.; Davison, Tracy; De Buck, Jeroen; Dumond, Mathieu; Elkin, Brett T.; Finnegan, Laura; Macbeth, Bryan J.; Nelson, Cait; Niptanatiak, Amanda; Sather, Shane; Schwantje, Helen M.; van der Meer, Frank; Kutz, Susan J.

    2016-01-01

    Northern ecosystems are currently experiencing unprecedented ecological change, largely driven by a rapidly changing climate. Pathogen range expansion, and emergence and altered patterns of infectious disease, are increasingly reported in wildlife at high latitudes. Understanding the causes and consequences of shifting pathogen diversity and host-pathogen interactions in these ecosystems is important for wildlife conservation, and for indigenous populations that depend on wildlife. Among the key questions are whether disease events are associated with endemic or recently introduced pathogens, and whether emerging strains are spreading throughout the region. In this study, we used a phylogenomic approach to address these questions of pathogen endemicity and spread for Erysipelothrix rhusiopathiae, an opportunistic multi-host bacterial pathogen associated with recent mortalities in arctic and boreal ungulate populations in North America. We isolated E. rhusiopathiae from carcasses associated with large-scale die-offs of muskoxen in the Canadian Arctic Archipelago, and from contemporaneous mortality events and/or population declines among muskoxen in northwestern Alaska and caribou and moose in western Canada. Bacterial genomic diversity differed markedly among these locations; minimal divergence was present among isolates from muskoxen in the Canadian Arctic, while in caribou and moose populations, strains from highly divergent clades were isolated from the same location, or even from within a single carcass. These results indicate that mortalities among northern ungulates are not associated with a single emerging strain of E. rhusiopathiae, and that alternate hypotheses need to be explored. Our study illustrates the value and limitations of bacterial genomic data for discriminating between ecological hypotheses of disease emergence, and highlights the importance of studying emerging pathogens within the broader context of environmental and host factors. PMID

  11. Infection of an Insect Vector with a Bacterial Plant Pathogen Increases Its Propensity for Dispersal.

    PubMed

    Martini, Xavier; Hoffmann, Mark; Coy, Monique R; Stelinski, Lukasz L; Pelz-Stelinski, Kirsten S

    2015-01-01

    The spread of vector-transmitted pathogens relies on complex interactions between host, vector and pathogen. In sessile plant pathosystems, the spread of a pathogen highly depends on the movement and mobility of the vector. However, questions remain as to whether and how pathogen-induced vector manipulations may affect the spread of a plant pathogen. Here we report for the first time that infection with a bacterial plant pathogen increases the probability of vector dispersal, and that such movement of vectors is likely manipulated by a bacterial plant pathogen. We investigated how Candidatus Liberibacter asiaticus (CLas) affects dispersal behavior, flight capacity, and the sexual attraction of its vector, the Asian citrus psyllid (Diaphorina citri Kuwayama). CLas is the putative causal agent of huanglongbing (HLB), which is a disease that threatens the viability of commercial citrus production worldwide. When D. citri developed on CLas-infected plants, short distance dispersal of male D. citri was greater compared to counterparts reared on uninfected plants. Flight by CLas-infected D. citri was initiated earlier and long flight events were more common than by uninfected psyllids, as measured by a flight mill apparatus. Additionally, CLas titers were higher among psyllids that performed long flights than psyllid that performed short flights. Finally, attractiveness of female D. citri that developed on infected plants to male conspecifics increased proportionally with increasing CLas bacterial titers measured within female psyllids. Our study indicates that the phytopathogen, CLas, may manipulate movement and mate selection behavior of their vectors, which is a possible evolved mechanism to promote their own spread. These results have global implications for both current HLB models of disease spread and control strategies.

  12. Infection of an Insect Vector with a Bacterial Plant Pathogen Increases Its Propensity for Dispersal

    PubMed Central

    Coy, Monique R.; Stelinski, Lukasz L.; Pelz-Stelinski, Kirsten S.

    2015-01-01

    The spread of vector-transmitted pathogens relies on complex interactions between host, vector and pathogen. In sessile plant pathosystems, the spread of a pathogen highly depends on the movement and mobility of the vector. However, questions remain as to whether and how pathogen-induced vector manipulations may affect the spread of a plant pathogen. Here we report for the first time that infection with a bacterial plant pathogen increases the probability of vector dispersal, and that such movement of vectors is likely manipulated by a bacterial plant pathogen. We investigated how Candidatus Liberibacter asiaticus (CLas) affects dispersal behavior, flight capacity, and the sexual attraction of its vector, the Asian citrus psyllid (Diaphorina citri Kuwayama). CLas is the putative causal agent of huanglongbing (HLB), which is a disease that threatens the viability of commercial citrus production worldwide. When D. citri developed on CLas-infected plants, short distance dispersal of male D. citri was greater compared to counterparts reared on uninfected plants. Flight by CLas-infected D. citri was initiated earlier and long flight events were more common than by uninfected psyllids, as measured by a flight mill apparatus. Additionally, CLas titers were higher among psyllids that performed long flights than psyllid that performed short flights. Finally, attractiveness of female D. citri that developed on infected plants to male conspecifics increased proportionally with increasing CLas bacterial titers measured within female psyllids. Our study indicates that the phytopathogen, CLas, may manipulate movement and mate selection behavior of their vectors, which is a possible evolved mechanism to promote their own spread. These results have global implications for both current HLB models of disease spread and control strategies. PMID:26083763

  13. Bacterial Genomics Reveal the Complex Epidemiology of an Emerging Pathogen in Arctic and Boreal Ungulates.

    PubMed

    Forde, Taya L; Orsel, Karin; Zadoks, Ruth N; Biek, Roman; Adams, Layne G; Checkley, Sylvia L; Davison, Tracy; De Buck, Jeroen; Dumond, Mathieu; Elkin, Brett T; Finnegan, Laura; Macbeth, Bryan J; Nelson, Cait; Niptanatiak, Amanda; Sather, Shane; Schwantje, Helen M; van der Meer, Frank; Kutz, Susan J

    2016-01-01

    Northern ecosystems are currently experiencing unprecedented ecological change, largely driven by a rapidly changing climate. Pathogen range expansion, and emergence and altered patterns of infectious disease, are increasingly reported in wildlife at high latitudes. Understanding the causes and consequences of shifting pathogen diversity and host-pathogen interactions in these ecosystems is important for wildlife conservation, and for indigenous populations that depend on wildlife. Among the key questions are whether disease events are associated with endemic or recently introduced pathogens, and whether emerging strains are spreading throughout the region. In this study, we used a phylogenomic approach to address these questions of pathogen endemicity and spread for Erysipelothrix rhusiopathiae, an opportunistic multi-host bacterial pathogen associated with recent mortalities in arctic and boreal ungulate populations in North America. We isolated E. rhusiopathiae from carcasses associated with large-scale die-offs of muskoxen in the Canadian Arctic Archipelago, and from contemporaneous mortality events and/or population declines among muskoxen in northwestern Alaska and caribou and moose in western Canada. Bacterial genomic diversity differed markedly among these locations; minimal divergence was present among isolates from muskoxen in the Canadian Arctic, while in caribou and moose populations, strains from highly divergent clades were isolated from the same location, or even from within a single carcass. These results indicate that mortalities among northern ungulates are not associated with a single emerging strain of E. rhusiopathiae, and that alternate hypotheses need to be explored. Our study illustrates the value and limitations of bacterial genomic data for discriminating between ecological hypotheses of disease emergence, and highlights the importance of studying emerging pathogens within the broader context of environmental and host factors.

  14. Bacterial genomics reveal the complex epidemiology of an emerging pathogen in arctic and boreal ungulates

    USGS Publications Warehouse

    Forde, Taya L.; Orsel, Karin; Zadoks, Ruth N.; Biek, Roman; Adams, Layne G.; Checkley, Sylvia L.; Davison, Tracy; De Buck, Jeroen; Dumond, Mathieu; Elkin, Brett T.; Finnegan, Laura; Macbeth, Bryan J.; Nelson, Cait; Niptanatiak, Amanda; Sather, Shane; Schwantje, Helen M.; van der Meer, Frank; Kutz, Susan J.

    2016-01-01

    Northern ecosystems are currently experiencing unprecedented ecological change, largely driven by a rapidly changing climate. Pathogen range expansion, and emergence and altered patterns of infectious disease, are increasingly reported in wildlife at high latitudes. Understanding the causes and consequences of shifting pathogen diversity and host-pathogen interactions in these ecosystems is important for wildlife conservation, and for indigenous populations that depend on wildlife. Among the key questions are whether disease events are associated with endemic or recently introduced pathogens, and whether emerging strains are spreading throughout the region. In this study, we used a phylogenomic approach to address these questions of pathogen endemicity and spread for Erysipelothrix rhusiopathiae, an opportunistic multi-host bacterial pathogen associated with recent mortalities in arctic and boreal ungulate populations in North America. We isolated E. rhusiopathiae from carcasses associated with large-scale die-offs of muskoxen in the Canadian Arctic Archipelago, and from contemporaneous mortality events and/or population declines among muskoxen in northwestern Alaska and caribou and moose in western Canada. Bacterial genomic diversity differed markedly among these locations; minimal divergence was present among isolates from muskoxen in the Canadian Arctic, while in caribou and moose populations, strains from highly divergent clades were isolated from the same location, or even from within a single carcass. These results indicate that mortalities among northern ungulates are not associated with a single emerging strain of E. rhusiopathiae, and that alternate hypotheses need to be explored. Our study illustrates the value and limitations of bacterial genomic data for discriminating between ecological hypotheses of disease emergence, and highlights the importance of studying emerging pathogens within the broader context of environmental and host factors.

  15. Distribution of Indigenous Bacterial Pathogens and Potential Pathogens Associated with Roof-Harvested Rainwater

    PubMed Central

    Dobrowsky, P. H.; De Kwaadsteniet, M.; Cloete, T. E.

    2014-01-01

    The harvesting of rainwater is gaining acceptance among many governmental authorities in countries such as Australia, Germany, and South Africa, among others. However, conflicting reports on the microbial quality of harvested rainwater have been published. To monitor the presence of potential pathogenic bacteria during high-rainfall periods, rainwater from 29 rainwater tanks was sampled on four occasions (during June and August 2012) in a sustainable housing project in Kleinmond, South Africa. This resulted in the collection of 116 harvested rainwater samples in total throughout the sampling period. The identities of the dominant, indigenous, presumptive pathogenic isolates obtained from the rainwater samples throughout the sampling period were confirmed through universal 16S rRNA PCR, and the results revealed that Pseudomonas (19% of samples) was the dominant genus isolated, followed by Aeromonas (16%), Klebsiella (11%), and Enterobacter (9%). PCR assays employing genus-specific primers also confirmed the presence of Aeromonas spp. (16%), Klebsiella spp. (47%), Legionella spp. (73%), Pseudomonas spp. (13%), Salmonella spp. (6%), Shigella spp. (27%), and Yersinia spp. (28%) in the harvested rainwater samples. In addition, on one sampling occasion, Giardia spp. were detected in 25% of the eight tank water samples analyzed. This study highlights the diverse array of pathogenic bacteria that persist in harvested rainwater during high-rainfall periods. The consumption of untreated harvested rainwater could thus pose a potential significant health threat to consumers, especially children and immunocompromised individuals, and it is recommended that harvested rainwater be treated for safe usage as an alternative water source. PMID:24487540

  16. Distribution of indigenous bacterial pathogens and potential pathogens associated with roof-harvested rainwater.

    PubMed

    Dobrowsky, P H; De Kwaadsteniet, M; Cloete, T E; Khan, W

    2014-04-01

    The harvesting of rainwater is gaining acceptance among many governmental authorities in countries such as Australia, Germany, and South Africa, among others. However, conflicting reports on the microbial quality of harvested rainwater have been published. To monitor the presence of potential pathogenic bacteria during high-rainfall periods, rainwater from 29 rainwater tanks was sampled on four occasions (during June and August 2012) in a sustainable housing project in Kleinmond, South Africa. This resulted in the collection of 116 harvested rainwater samples in total throughout the sampling period. The identities of the dominant, indigenous, presumptive pathogenic isolates obtained from the rainwater samples throughout the sampling period were confirmed through universal 16S rRNA PCR, and the results revealed that Pseudomonas (19% of samples) was the dominant genus isolated, followed by Aeromonas (16%), Klebsiella (11%), and Enterobacter (9%). PCR assays employing genus-specific primers also confirmed the presence of Aeromonas spp. (16%), Klebsiella spp. (47%), Legionella spp. (73%), Pseudomonas spp. (13%), Salmonella spp. (6%), Shigella spp. (27%), and Yersinia spp. (28%) in the harvested rainwater samples. In addition, on one sampling occasion, Giardia spp. were detected in 25% of the eight tank water samples analyzed. This study highlights the diverse array of pathogenic bacteria that persist in harvested rainwater during high-rainfall periods. The consumption of untreated harvested rainwater could thus pose a potential significant health threat to consumers, especially children and immunocompromised individuals, and it is recommended that harvested rainwater be treated for safe usage as an alternative water source.

  17. A window of opportunity to control the bacterial pathogen Pseudomonas aeruginosa combining antibiotics and phages.

    PubMed

    Torres-Barceló, Clara; Arias-Sánchez, Flor I; Vasse, Marie; Ramsayer, Johan; Kaltz, Oliver; Hochberg, Michael E

    2014-01-01

    The evolution of antibiotic resistance in bacteria is a global concern and the use of bacteriophages alone or in combined therapies is attracting increasing attention as an alternative. Evolutionary theory predicts that the probability of bacterial resistance to both phages and antibiotics will be lower than to either separately, due for example to fitness costs or to trade-offs between phage resistance mechanisms and bacterial growth. In this study, we assess the population impacts of either individual or combined treatments of a bacteriophage and streptomycin on the nosocomial pathogen Pseudomonas aeruginosa. We show that combining phage and antibiotics substantially increases bacterial control compared to either separately, and that there is a specific time delay in antibiotic introduction independent of antibiotic dose, that minimizes both bacterial density and resistance to either antibiotics or phage. These results have implications for optimal combined therapeutic approaches.

  18. Human caspase-4 mediates noncanonical inflammasome activation against gram-negative bacterial pathogens

    PubMed Central

    Casson, Cierra N.; Yu, Janet; Reyes, Valeria M.; Taschuk, Frances O.; Yadav, Anjana; Copenhaver, Alan M.; Nguyen, Hieu T.; Collman, Ronald G.; Shin, Sunny

    2015-01-01

    Inflammasomes are critical for host defense against bacterial pathogens. In murine macrophages infected by gram-negative bacteria, the canonical inflammasome activates caspase-1 to mediate pyroptotic cell death and release of IL-1 family cytokines. Additionally, a noncanonical inflammasome controlled by caspase-11 induces cell death and IL-1 release. However, humans do not encode caspase-11. Instead, humans encode two putative orthologs: caspase-4 and caspase-5. Whether either ortholog functions similar to caspase-11 is poorly defined. Therefore, we sought to define the inflammatory caspases in primary human macrophages that regulate inflammasome responses to gram-negative bacteria. We find that human macrophages activate inflammasomes specifically in response to diverse gram-negative bacterial pathogens that introduce bacterial products into the host cytosol using specialized secretion systems. In primary human macrophages, IL-1β secretion requires the caspase-1 inflammasome, whereas IL-1α release and cell death are caspase-1–independent. Instead, caspase-4 mediates IL-1α release and cell death. Our findings implicate human caspase-4 as a critical regulator of noncanonical inflammasome activation that initiates defense against bacterial pathogens in primary human macrophages. PMID:25964352

  19. A bacterial siren song: intimate interactions between neutrophils and pathogenic Neisseria

    PubMed Central

    Criss, Alison K.; Seifert, H. Steven

    2012-01-01

    Preface Neisseria gonorrhoeae and Neisseria meningitidis are Gram-negative bacterial pathogens that are exquisitely adapted for growth at human mucosal surfaces and for efficient transmission between hosts. One factor that is essential to neisserial pathogenesis is the interaction between the bacteria and neutrophils, which are recruited in high numbers during infection. Although this vigorous host response could simply reflect effective immune recognition of the bacteria, there is mounting evidence that in fact these obligate human pathogens manipulate the innate immune response to promote infectious processes. This Review summarizes the mechanisms used by pathogenic neisseriae to resist and modulate the antimicrobial activities of neutrophils. It also details some of the major outstanding questions about the Neisseria–neutrophil relationship and proposes potential benefits of this relationship for the pathogen. PMID:22290508

  20. Bacterial Autophagy: Offense and Defense at the Host-Pathogen Interface.

    PubMed

    Casanova, James E

    2017-09-01

    Autophagy is a fundamental cellular process used for the turnover and recycling of cytosolic components and damaged organelles. Originally characterized as a response to cellular stress, it now is well established that autophagy also is used as a defensive mechanism to combat the infection of host cells by intracellular pathogens. However, although this defensive strategy does limit the proliferation of most pathogens within their host cells, successful pathogens have evolved countermeasures that subvert or circumvent the autophagic response. In this review, we discuss the mechanisms used by a number of these pathogens to escape autophagy, with a particular focus on Salmonella enterica serovar Typhimurium, which has been the most extensively studied example. We also discuss the consequences of bacterial autophagy for the broader innate immune response.

  1. Development of Quorum-Based Anti-Virulence Therapeutics Targeting Gram-Negative Bacterial Pathogens

    PubMed Central

    Tay, Song Buck; Yew, Wen Shan

    2013-01-01

    Quorum sensing is a cell density-dependent signaling phenomenon used by bacteria for coordination of population-wide phenotypes, such as expression of virulence genes, antibiotic resistance and biofilm formation. Lately, disruption of bacterial communication has emerged as an anti-virulence strategy with enormous therapeutic potential given the increasing incidences of drug resistance in pathogenic bacteria. The quorum quenching therapeutic approach promises a lower risk of resistance development, since interference with virulence generally does not affect the growth and fitness of the bacteria and, hence, does not exert an associated selection pressure for drug-resistant strains. With better understanding of bacterial communication networks and mechanisms, many quorum quenching methods have been developed against various clinically significant bacterial pathogens. In particular, Gram-negative bacteria are an important group of pathogens, because, collectively, they are responsible for the majority of hospital-acquired infections. Here, we discuss the current understanding of existing quorum sensing mechanisms and present important inhibitory strategies that have been developed against this group of pathogenic bacteria. PMID:23939429

  2. Bacterial quorum sensing inhibitors: attractive alternatives for control of infectious pathogens showing multiple drug resistance.

    PubMed

    Bhardwaj, Ashima K; Vinothkumar, Kittappa; Rajpara, Neha

    2013-04-01

    Quorum sensing (QS) is a bacterial communication process that depends on the bacterial population density. It involves small diffusible signaling molecules which activate the expression of myriad genes that control diverse array of functions like bioluminescence, virulence, biofilm formation, sporulation, to name a few. Since QS is responsible for virulence in the clinically relevant bacteria, inhibition of QS appears to be a promising strategy to control these pathogenic bacteria. With indiscriminate use of antibiotics, there has been an alarming increase in the number of antibiotic resistant pathogens. Antibiotics are no longer the magic bullets they were once thought to be and therefore there is a need for development of new antibiotics and/or other novel strategies to combat the infections caused by multidrug resistant organisms. Quorum sensing inhibition or quorum quenching has been pursued as one of such novel strategies. While antibiotics kill or slow down the growth of bacteria, quorum sensing inhibitors (QSIs) or quorum quenchers (QQs) attenuate bacterial virulence. A large body of work on QS has been carried out in deadly pathogens like Pseudomonas aeruginosa, Staphylococcus aureus, Vibrio fischeri, V. harveyi, Escherichia coli and V. cholerae etc to unravel the mechanisms of QS as well as identify and study QSIs. This review describes various aspects of QS, QSI, different model systems to study these phenomena and recent patents on various QSIs. It suggests QSIs as attractive alternatives for controlling human, animal and plant pathogens and their utility in agriculture and other industries.

  3. Molecular mechanisms underlying the emergence of bacterial pathogens: an ecological perspective.

    PubMed

    Bartoli, Claudia; Roux, Fabrice; Lamichhane, Jay Ram

    2016-02-01

    The rapid emergence of new bacterial diseases negatively affects both human health and agricultural productivity. Although the molecular mechanisms underlying these disease emergences are shared between human- and plant-pathogenic bacteria, not much effort has been made to date to understand disease emergences caused by plant-pathogenic bacteria. In particular, there is a paucity of information in the literature on the role of environmental habitats in which plant-pathogenic bacteria evolve and on the stress factors to which these microbes are unceasingly exposed. In this microreview, we focus on three molecular mechanisms underlying pathogenicity in bacteria, namely mutations, genomic rearrangements and the acquisition of new DNA sequences through horizontal gene transfer (HGT). We briefly discuss the role of these mechanisms in bacterial disease emergence and elucidate how the environment can influence the occurrence and regulation of these molecular mechanisms by directly impacting disease emergence. The understanding of such molecular evolutionary mechanisms and their environmental drivers will represent an important step towards predicting bacterial disease emergence and developing sustainable management strategies for crops.

  4. The widespread plant-colonizing bacterial species Pseudomonas syringae detects and exploits an extracellular pool of choline in hosts.

    PubMed

    Chen, Chiliang; Li, Shanshan; McKeever, Dana R; Beattie, Gwyn A

    2013-09-01

    The quaternary ammonium compound (QAC) choline is a major component of membrane lipids in eukaryotes and, if available to microbial colonists of plants, could provide benefits for growth and protection from stress. Free choline is found in homogenized plant tissues, but its subcellular location and availability to plant microbes are not known. Whole-cell bacterial bioreporters of the phytopathogen Pseudomonas syringae were constructed that couple a QAC-responsive transcriptional fusion with well-characterized bacterial QAC transporters. These bioreporters demonstrated the presence of abundant free choline compounds released from germinating seeds and seedlings of the bean Phaseolus vulgaris, and a smaller but consistently detectable amount of QACs, probably choline, from leaves. The localization of P. syringae bioreporter cells to the surface and intercellular sites of plant tissues demonstrated the extracellular location of these QAC pools. Moreover, P. syringae mutants that were deficient in the uptake of choline compounds exhibited reduced fitness on leaves, highlighting the importance of extracellular choline to P. syringae on leaves. Our data support a model in which this choline pool is derived from the phospholipid phosphatidylcholine through plant-encoded phospholipases that release choline into the intercellular spaces of plant tissues, such as for membrane lipid recycling. The consequent extracellular release of choline compounds enables their interception and exploitation by plant-associated microbes, and thus provides a selective advantage for microbes such as P. syringae that are adapted to maximally exploit choline.

  5. Understanding the Impact of Drought on Foliar and Xylem Invading Bacterial Pathogen Stress in Chickpea

    PubMed Central

    Sinha, Ranjita; Gupta, Aarti; Senthil-Kumar, Muthappa

    2016-01-01

    In field conditions, plants are concurrently exposed to multiple stresses, where one stressor impacts the plant's response to another stressor, and the resultant net effect of these stresses differs from individual stress response. The present study investigated the effect of drought stress on interaction of chickpea with Pseudomonas syringae pv. phaseolicola (Psp; foliar pathogen) and Ralstonia solanacearum (Rs; xylem inhabiting wilt causing pathogen), respectively, and the net-effect of combined stress on chlorophyll content and cell death. Two type of stress treatments were used to study the influence of each stress factor during combined stress, viz., imposition of drought stress followed by pathogen challenge (DP), and pathogen inoculated plants imposed with drought in course of pathogen infection (PD). Drought stress was imposed at different levels with pathogen inoculum to understand the influence of different stress intensities on stress interaction and their net impact. Drought stressed chickpea plants challenged with Psp infection (DPsp) showed reduced in planta bacterial number compared to Psp infection alone. Similarly, Rs infection of chickpea plants showed reduced in planta bacterial number under severe drought stress. Combined drought and Psp (DPsp) infected plants showed decreased cell death compared to plants infected only with Psp but the extent of cell death was similar to drought stressed plants. Similarly, chlorophyll content in plants under combined stress was similar to the individual drought stressed plants; however, the chlorophyll content was more compared to pathogen only infected plants. Under combined drought and Rs infection (DRs), cell death was similar to individual drought stress but significantly less compared to only Rs infected plants. Altogether, the study proposes that both stress interaction and net effect of combined stress could be majorly influenced by first occurring stress, for example, drought stress in DP treatment. In

  6. Profiling the secretome and extracellular proteome of the potato late blight pathogen Phytophthora infestans.

    PubMed

    Meijer, Harold J G; Mancuso, Francesco M; Espadas, Guadalupe; Seidl, Michael F; Chiva, Cristina; Govers, Francine; Sabidó, Eduard

    2014-08-01

    Oomycetes are filamentous organisms that cause notorious diseases, several of which have a high economic impact. Well known is Phytophthora infestans, the causal agent of potato late blight. Previously, in silico analyses of the genome and transcriptome of P. infestans resulted in the annotation of a large number of genes encoding proteins with an N-terminal signal peptide. This set is collectively referred to as the secretome and comprises proteins involved in, for example, cell wall growth and modification, proteolytic processes, and the promotion of successful invasion of plant cells. So far, proteomic profiling in oomycetes was primarily focused on subcellular, intracellular or cell wall fractions; the extracellular proteome has not been studied systematically. Here we present the first comprehensive characterization of the in vivo secretome and extracellular proteome of P. infestans. We have used mass spectrometry to analyze P. infestans proteins present in seven different growth media with mycelial cultures and this resulted in the consistent identification of over two hundred proteins. Gene ontology classification pinpointed proteins involved in cell wall modifications, pathogenesis, defense responses, and proteolytic processes. Moreover, we found members of the RXLR and CRN effector families as well as several proteins lacking an obvious signal peptide. The latter were confirmed to be bona fide extracellular proteins and this suggests that, similar to other organisms, oomycetes exploit non-conventional secretion mechanisms to transfer certain proteins to the extracellular environment.

  7. Profiling the Secretome and Extracellular Proteome of the Potato Late Blight Pathogen Phytophthora infestans

    PubMed Central

    Meijer, Harold J. G.; Mancuso, Francesco M.; Espadas, Guadalupe; Seidl, Michael F.; Chiva, Cristina; Govers, Francine; Sabidó, Eduard

    2014-01-01

    Oomycetes are filamentous organisms that cause notorious diseases, several of which have a high economic impact. Well known is Phytophthora infestans, the causal agent of potato late blight. Previously, in silico analyses of the genome and transcriptome of P. infestans resulted in the annotation of a large number of genes encoding proteins with an N-terminal signal peptide. This set is collectively referred to as the secretome and comprises proteins involved in, for example, cell wall growth and modification, proteolytic processes, and the promotion of successful invasion of plant cells. So far, proteomic profiling in oomycetes was primarily focused on subcellular, intracellular or cell wall fractions; the extracellular proteome has not been studied systematically. Here we present the first comprehensive characterization of the in vivo secretome and extracellular proteome of P. infestans. We have used mass spectrometry to analyze P. infestans proteins present in seven different growth media with mycelial cultures and this resulted in the consistent identification of over two hundred proteins. Gene ontology classification pinpointed proteins involved in cell wall modifications, pathogenesis, defense responses, and proteolytic processes. Moreover, we found members of the RXLR and CRN effector families as well as several proteins lacking an obvious signal peptide. The latter were confirmed to be bona fide extracellular proteins and this suggests that, similar to other organisms, oomycetes exploit non-conventional secretion mechanisms to transfer certain proteins to the extracellular environment. PMID:24872595

  8. Copper Transport and Trafficking at the Host–Bacterial Pathogen Interface

    PubMed Central

    2015-01-01

    Conspectus The human innate immune system has evolved the means to reduce the bioavailability of first-row late d-block transition metal ions to invading microbial pathogens in a process termed “nutritional immunity”. Transition metals from Mn(II) to Zn(II) function as metalloenzyme cofactors in all living cells, and the successful pathogen is capable of mounting an adaptive response to mitigate the effects of host control of transition metal bioavailability. Emerging evidence suggests that Mn, Fe, and Zn are withheld from the pathogen in classically defined nutritional immunity, while Cu is used to kill invading microorganisms. This Account summarizes new molecular-level insights into copper trafficking across cell membranes from studies of a number of important bacterial pathogens and model organisms, including Escherichia coli, Salmonella species, Mycobacterium tuberculosis, and Streptococcus pneumoniae, to illustrate general principles of cellular copper resistance. Recent highlights of copper chemistry at the host–microbial pathogen interface include the first high resolution structures and functional characterization of a Cu(I)-effluxing P1B-ATPase, a new class of bacterial copper chaperone, a fungal Cu-only superoxide dismutase SOD5, and the discovery of a small molecule Cu-bound SOD mimetic. Successful harnessing by the pathogen of host-derived bactericidal Cu to reduce the bacterial load of reactive oxygen species (ROS) is an emerging theme; in addition, recent studies continue to emphasize the importance of short lifetime protein–protein interactions that orchestrate the channeling of Cu(I) from donor to target without dissociation into bulk solution; this, in turn, mitigates the off-pathway effects of Cu(I) toxicity in both the periplasm in Gram negative organisms and in the bacterial cytoplasm. It is unclear as yet, outside of the photosynthetic bacteria, whether Cu(I) is trafficked to other cellular destinations, for example, to cuproenzymes or

  9. Ralstonia solanacearum, a widespread bacterial plant pathogen in the post-genomic era.

    PubMed

    Peeters, Nemo; Guidot, Alice; Vailleau, Fabienne; Valls, Marc

    2013-09-01

    Ralstonia solanacearum is a soil-borne bacterium causing the widespread disease known as bacterial wilt. Ralstonia solanacearum is also the causal agent of Moko disease of banana and brown rot of potato. Since the last R. solanacearum pathogen profile was published 10 years ago, studies concerning this plant pathogen have taken a genomic and post-genomic direction. This was pioneered by the first sequenced and annotated genome for a major plant bacterial pathogen and followed by many more genomes in subsequent years. All molecular features studied now have a genomic flavour. In the future, this will help in connecting the classical field of pathology and diversity studies with the gene content of specific strains. In this review, we summarize the recent research on this bacterial pathogen, including strain classification, host range, pathogenicity determinants, regulation of virulence genes, type III effector repertoire, effector-triggered immunity, plant signalling in response to R. solanacearum, as well as a review of different new pathosystems. Bacteria; Proteobacteria; β subdivision; Ralstonia group; genus Ralstonia. Ralstonia solanacearum is the agent of bacterial wilt of plants, characterized by a sudden wilt of the whole plant. Typically, stem cross-sections will ooze a slimy bacterial exudate. In the case of Moko disease of banana and brown rot of potato, there is also visible bacterial colonization of banana fruit and potato tuber. As a soil-borne pathogen, infected fields can rarely be reused, even after rotation with nonhost plants. The disease is controlled by the use of resistant and tolerant plant cultivars. The prevention of spread of the disease has been achieved, in some instances, by the application of strict prophylactic sanitation practices. Stock centre: International Centre for Microbial Resources-French Collection for Plant-associated Bacteria CIRM-CFBP, IRHS UMR 1345 INRA-ACO-UA, 42 rue Georges Morel, 49070 Beaucouzé Cedex, France

  10. Copper transport and trafficking at the host-bacterial pathogen interface.

    PubMed

    Fu, Yue; Chang, Feng-Ming James; Giedroc, David P

    2014-12-16

    CONSPECTUS: The human innate immune system has evolved the means to reduce the bioavailability of first-row late d-block transition metal ions to invading microbial pathogens in a process termed "nutritional immunity". Transition metals from Mn(II) to Zn(II) function as metalloenzyme cofactors in all living cells, and the successful pathogen is capable of mounting an adaptive response to mitigate the effects of host control of transition metal bioavailability. Emerging evidence suggests that Mn, Fe, and Zn are withheld from the pathogen in classically defined nutritional immunity, while Cu is used to kill invading microorganisms. This Account summarizes new molecular-level insights into copper trafficking across cell membranes from studies of a number of important bacterial pathogens and model organisms, including Escherichia coli, Salmonella species, Mycobacterium tuberculosis, and Streptococcus pneumoniae, to illustrate general principles of cellular copper resistance. Recent highlights of copper chemistry at the host-microbial pathogen interface include the first high resolution structures and functional characterization of a Cu(I)-effluxing P1B-ATPase, a new class of bacterial copper chaperone, a fungal Cu-only superoxide dismutase SOD5, and the discovery of a small molecule Cu-bound SOD mimetic. Successful harnessing by the pathogen of host-derived bactericidal Cu to reduce the bacterial load of reactive oxygen species (ROS) is an emerging theme; in addition, recent studies continue to emphasize the importance of short lifetime protein-protein interactions that orchestrate the channeling of Cu(I) from donor to target without dissociation into bulk solution; this, in turn, mitigates the off-pathway effects of Cu(I) toxicity in both the periplasm in Gram negative organisms and in the bacterial cytoplasm. It is unclear as yet, outside of the photosynthetic bacteria, whether Cu(I) is trafficked to other cellular destinations, for example, to cuproenzymes or other

  11. Genomic Survey of Pathogenicity Determinants and VNTR Markers in the Cassava Bacterial Pathogen Xanthomonas axonopodis pv. Manihotis Strain CIO151

    PubMed Central

    Arrieta-Ortiz, Mario L.; Rodríguez-R, Luis M.; Pérez-Quintero, Álvaro L.; Poulin, Lucie; Díaz, Ana C.; Arias Rojas, Nathalia; Trujillo, Cesar; Restrepo Benavides, Mariana; Bart, Rebecca; Boch, Jens; Boureau, Tristan; Darrasse, Armelle; David, Perrine; Dugé de Bernonville, Thomas; Fontanilla, Paula; Gagnevin, Lionel; Guérin, Fabien; Jacques, Marie-Agnès; Lauber, Emmanuelle; Lefeuvre, Pierre; Medina, Cesar; Medina, Edgar; Montenegro, Nathaly; Muñoz Bodnar, Alejandra; Noël, Laurent D.; Ortiz Quiñones, Juan F.; Osorio, Daniela; Pardo, Carolina; Patil, Prabhu B.; Poussier, Stéphane; Pruvost, Olivier; Robène-Soustrade, Isabelle; Ryan, Robert P.; Tabima, Javier; Urrego Morales, Oscar G.; Vernière, Christian; Carrere, Sébastien; Verdier, Valérie; Szurek, Boris; Restrepo, Silvia; López, Camilo

    2013-01-01

    Xanthomonas axonopodis pv. manihotis (Xam) is the causal agent of bacterial blight of cassava, which is among the main components of human diet in Africa and South America. Current information about the molecular pathogenicity factors involved in the infection process of this organism is limited. Previous studies in other bacteria in this genus suggest that advanced draft genome sequences are valuable resources for molecular studies on their interaction with plants and could provide valuable tools for diagnostics and detection. Here we have generated the first manually annotated high-quality draft genome sequence of Xam strain CIO151. Its genomic structure is similar to that of other xanthomonads, especially Xanthomonas euvesicatoria and Xanthomonas citri pv. citri species. Several putative pathogenicity factors were identified, including type III effectors, cell wall-degrading enzymes and clusters encoding protein secretion systems. Specific characteristics in this genome include changes in the xanthomonadin cluster that could explain the lack of typical yellow color in all strains of this pathovar and the presence of 50 regions in the genome with atypical nucleotide composition. The genome sequence was used to predict and evaluate 22 variable number of tandem repeat (VNTR) loci that were subsequently demonstrated as polymorphic in representative Xam strains. Our results demonstrate that Xanthomonas axonopodis pv. manihotis strain CIO151 possesses ten clusters of pathogenicity factors conserved within the genus Xanthomonas. We report 126 genes that are potentially unique to Xam, as well as potential horizontal transfer events in the history of the genome. The relation of these regions with virulence and pathogenicity could explain several aspects of the biology of this pathogen, including its ability to colonize both vascular and non-vascular tissues of cassava plants. A set of 16 robust, polymorphic VNTR loci will be useful to develop a multi-locus VNTR analysis

  12. Genomic survey of pathogenicity determinants and VNTR markers in the cassava bacterial pathogen Xanthomonas axonopodis pv. Manihotis strain CIO151.

    PubMed

    Arrieta-Ortiz, Mario L; Rodríguez-R, Luis M; Pérez-Quintero, Álvaro L; Poulin, Lucie; Díaz, Ana C; Arias Rojas, Nathalia; Trujillo, Cesar; Restrepo Benavides, Mariana; Bart, Rebecca; Boch, Jens; Boureau, Tristan; Darrasse, Armelle; David, Perrine; Dugé de Bernonville, Thomas; Fontanilla, Paula; Gagnevin, Lionel; Guérin, Fabien; Jacques, Marie-Agnès; Lauber, Emmanuelle; Lefeuvre, Pierre; Medina, Cesar; Medina, Edgar; Montenegro, Nathaly; Muñoz Bodnar, Alejandra; Noël, Laurent D; Ortiz Quiñones, Juan F; Osorio, Daniela; Pardo, Carolina; Patil, Prabhu B; Poussier, Stéphane; Pruvost, Olivier; Robène-Soustrade, Isabelle; Ryan, Robert P; Tabima, Javier; Urrego Morales, Oscar G; Vernière, Christian; Carrere, Sébastien; Verdier, Valérie; Szurek, Boris; Restrepo, Silvia; López, Camilo; Koebnik, Ralf; Bernal, Adriana

    2013-01-01

    Xanthomonas axonopodis pv. manihotis (Xam) is the causal agent of bacterial blight of cassava, which is among the main components of human diet in Africa and South America. Current information about the molecular pathogenicity factors involved in the infection process of this organism is limited. Previous studies in other bacteria in this genus suggest that advanced draft genome sequences are valuable resources for molecular studies on their interaction with plants and could provide valuable tools for diagnostics and detection. Here we have generated the first manually annotated high-quality draft genome sequence of Xam strain CIO151. Its genomic structure is similar to that of other xanthomonads, especially Xanthomonas euvesicatoria and Xanthomonas citri pv. citri species. Several putative pathogenicity factors were identified, including type III effectors, cell wall-degrading enzymes and clusters encoding protein secretion systems. Specific characteristics in this genome include changes in the xanthomonadin cluster that could explain the lack of typical yellow color in all strains of this pathovar and the presence of 50 regions in the genome with atypical nucleotide composition. The genome sequence was used to predict and evaluate 22 variable number of tandem repeat (VNTR) loci that were subsequently demonstrated as polymorphic in representative Xam strains. Our results demonstrate that Xanthomonas axonopodis pv. manihotis strain CIO151 possesses ten clusters of pathogenicity factors conserved within the genus Xanthomonas. We report 126 genes that are potentially unique to Xam, as well as potential horizontal transfer events in the history of the genome. The relation of these regions with virulence and pathogenicity could explain several aspects of the biology of this pathogen, including its ability to colonize both vascular and non-vascular tissues of cassava plants. A set of 16 robust, polymorphic VNTR loci will be useful to develop a multi-locus VNTR analysis

  13. Crystal Structures of Cif from Bacterial Pathogens Photorhabdus luminescens and Burkholderia pseudomallei

    PubMed Central

    Crow, Allister; Race, Paul R.; Jubelin, Grégory; Varela Chavez, Carolina; Escoubas, Jean-Michel; Oswald, Eric; Banfield, Mark J.

    2009-01-01

    A pre-requisite for bacterial pathogenesis is the successful interaction of a pathogen with a host. One mechanism used by a broad range of Gram negative bacterial pathogens is to deliver effector proteins directly into host cells through a dedicated type III secretion system where they modulate host cell function. The cycle inhibiting factor (Cif) family of effector proteins, identified in a growing number of pathogens that harbour functional type III secretion systems and have a wide host range, arrest the eukaryotic cell cycle. Here, the crystal structures of Cifs from the insect pathogen/nematode symbiont Photorhabdus luminescens (a γ-proteobacterium) and human pathogen Burkholderia pseudomallei (a β-proteobacterium) are presented. Both of these proteins adopt an overall fold similar to the papain sub-family of cysteine proteases, as originally identified in the structure of a truncated form of Cif from Enteropathogenic E. coli (EPEC), despite sharing only limited sequence identity. The structure of an N-terminal region, referred to here as the ‘tail-domain’ (absent in the EPEC Cif structure), suggests a surface likely to be involved in host-cell substrate recognition. The conformation of the Cys-His-Gln catalytic triad is retained, and the essential cysteine is exposed to solvent and addressable by small molecule reagents. These structures and biochemical work contribute to the rapidly expanding literature on Cifs, and direct further studies to better understand the molecular details of the activity of these proteins. PMID:19440549

  14. Crystal structures of Cif from bacterial pathogens Photorhabdus luminescens and Burkholderia pseudomallei.

    PubMed

    Crow, Allister; Race, Paul R; Jubelin, Grégory; Varela Chavez, Carolina; Escoubas, Jean-Michel; Oswald, Eric; Banfield, Mark J

    2009-01-01

    A pre-requisite for bacterial pathogenesis is the successful interaction of a pathogen with a host. One mechanism used by a broad range of Gram negative bacterial pathogens is to deliver effector proteins directly into host cells through a dedicated type III secretion system where they modulate host cell function. The cycle inhibiting factor (Cif) family of effector proteins, identified in a growing number of pathogens that harbour functional type III secretion systems and have a wide host range, arrest the eukaryotic cell cycle. Here, the crystal structures of Cifs from the insect pathogen/nematode symbiont Photorhabdus luminescens (a gamma-proteobacterium) and human pathogen Burkholderia pseudomallei (a beta-proteobacterium) are presented. Both of these proteins adopt an overall fold similar to the papain sub-family of cysteine proteases, as originally identified in the structure of a truncated form of Cif from Enteropathogenic E. coli (EPEC), despite sharing only limited sequence identity. The structure of an N-terminal region, referred to here as the 'tail-domain' (absent in the EPEC Cif structure), suggests a surface likely to be involved in host-cell substrate recognition. The conformation of the Cys-His-Gln catalytic triad is retained, and the essential cysteine is exposed to solvent and addressable by small molecule reagents. These structures and biochemical work contribute to the rapidly expanding literature on Cifs, and direct further studies to better understand the molecular details of the activity of these proteins.

  15. Detection of Pathogenic Biofilms with Bacterial Amyloid Targeting Fluorescent Probe, CDy11.

    PubMed

    Kim, Jun-Young; Sahu, Srikanta; Yau, Yin-Hoe; Wang, Xu; Shochat, Susana Geifman; Nielsen, Per Halkjær; Dueholm, Morten Simonsen; Otzen, Daniel E; Lee, Jungyeol; Delos Santos, May Margarette Salido; Yam, Joey Kuok Hoong; Kang, Nam-Young; Park, Sung-Jin; Kwon, Hawyoung; Seviour, Thomas; Yang, Liang; Givskov, Michael; Chang, Young-Tae

    2016-01-13

    Bacterial biofilms are responsible for a wide range of persistent infections. In the clinic, diagnosis of biofilm-associated infections relies heavily on culturing methods, which fail to detect nonculturable bacteria. Identification of novel fluorescent probes for biofilm imaging will greatly facilitate diagnosis of pathogenic bacterial infection. Herein, we report a novel fluorescent probe, CDy11 (compound of designation yellow 11), which targets amyloid in the Pseudomonas aeruginosa biofilm matrix through a diversity oriented fluorescent library approach (DOFLA). CDy11 was further demonstrated for in vivo imaging of P. aeruginosa in implant and corneal infection mice models.

  16. Bacterial blight of soybean: Regulation of a pathogen gene determining host cultivar specificity

    SciTech Connect

    Huynh, T.V.; Dahlbeck, D.; Staskawicz, B.J. )

    1989-09-22

    Soybean cultivars resistant to Pseudomonas syringae pathovar glycinea (Psg), the causal agent of bacterial blight, exhibit a hypersensitive (necrosis) reaction (HR) to infection. Psg strains carrying the avrB gene elicit the HR in soybean cultivars carrying the resistance gene Rpg1. Psg expressing avrB at a high level and capable of eliciting the HR in the absence of de novo bacterial RNA synthesis have been obtained in in vitro culture. Nutritional signals and regions within the Psg hrp gene cluster, an approximately 20-kilobase genomic region also necessary for pathogenicity, control avrB transcription.

  17. Short term memory of Caenorhabditis elegans against bacterial pathogens involves CREB transcription factor.

    PubMed

    Prithika, Udayakumar; Vikneswari, Ramaraj; Balamurugan, Krishnaswamy

    2017-04-01

    One of the key issues pertaining to the control of memory is to respond to a consistently changing environment or microbial niche present in it. Human cyclic AMP response element binding protein (CREB) transcription factor which plays a crucial role in memory has a homolog in C. elegans, crh-1. crh-1 appears to influence memory processes to certain extent by habituation of the host to a particular environment. The discrimination between the pathogen and a non-pathogen is essential for C. elegans in a microbial niche which determines its survival. Training the nematodes in the presence of a virulent pathogen (S. aureus) and an opportunistic pathogen (P. mirabilis) separately exhibits a different behavioural paradigm. This appears to be dependent on the CREB transcription factor. Here we show that C. elegans homolog crh-1 helps in memory response for a short term against the interacting pathogens. Following conditioning of the nematodes to S. aureus and P. mirabilis, the wild type nematodes exhibited a positive response towards the respective pathogens which diminished slowly after 2h. By contrast, the crh-1 deficient nematodes had a defective memory post conditioning. The molecular data reinforces the importance of crh-1 gene in retaining the memory of nematode. Our results also suggest that involvement of neurotransmitters play a crucial role in modulating the memory of the nematode with the assistance of CREB. Therefore, we elucidate that CREB is responsible for the short term memory response in C. elegans against bacterial pathogens.

  18. Coinfection of tick cell lines has variable effects on replication of intracellular bacterial and viral pathogens.

    PubMed

    Moniuszko, Anna; Rückert, Claudia; Alberdi, M Pilar; Barry, Gerald; Stevenson, Brian; Fazakerley, John K; Kohl, Alain; Bell-Sakyi, Lesley

    2014-06-01

    Ticks transmit various human and animal microbial pathogens and may harbour more than one pathogen simultaneously. Both viruses and bacteria can trigger, and may subsequently suppress, vertebrate host and arthropod vector anti-microbial responses. Microbial coinfection of ticks could lead to an advantage or disadvantage for one or more of the microorganisms. In this preliminary study, cell lines derived from the ticks Ixodes scapularis and Ixodes ricinus were infected sequentially with 2 arthropod-borne pathogens, Borrelia burgdorferi s.s., Ehrlichia ruminantium, or Semliki Forest virus (SFV), and the effect of coinfection on the replication of these pathogens was measured. Prior infection of tick cell cultures with the spirochaete B. burgdorferi enhanced subsequent replication of the rickettsial pathogen E. ruminantium whereas addition of spirochaetes to cells infected with E. ruminantium had no effect on growth of the latter. Both prior and subsequent presence of B. burgdorferi also had a positive effect on SFV replication. Presence of E. ruminantium or SFV had no measurable effect on B. burgdorferi growth. In tick cells infected first with E. ruminantium and then with SFV, virus replication was significantly higher across all time points measured (24, 48, 72h post infection), while presence of the virus had no detectable effect on bacterial growth. When cells were infected first with SFV and then with E. ruminantium, there was no effect on replication of either pathogen. The results of this preliminary study indicate that interplay does occur between different pathogens during infection of tick cells. Further study is needed to determine if this results from direct pathogen-pathogen interaction or from effects on host cell defences, and to determine if these observations also apply in vivo in ticks. If presence of one pathogen in the tick vector results in increased replication of another, this could have implications for disease transmission and incidence

  19. Bacterial pathogens isolated from cockroaches trapped from paediatric wards in peninsular Malaysia.

    PubMed

    Oothuman, P; Jeffery, J; Aziz, A H; Abu Bakar, E; Jegathesan, M

    1989-01-01

    A survey was conducted in 4 paediatric wards in Malaysia to determine the distribution of various species of cockroaches and to examine their gut contents for bacteria. Cockroaches were trapped from food dispensing areas (kitchens), store rooms, cupboards and open wards. 104 cockroaches were caught, consisting of Periplaneta americana (67.3%), Blattella germanica (26%), P. brunnea (4.8%), and Supella longipalpa (1.9%). Bacteria were isolated from all cockroaches except 3 P. americana. Many bacterial species were identified, including the pathogenic and potentially pathogenic species Shigella boydii, S. dysenteriae, Salmonella typhimurium, Klebseilla oxytoca, K. ozaena and Serratia marcescens.

  20. Nucleic Acid-based Detection of Bacterial Pathogens Using Integrated Microfluidic Platform Systems

    PubMed Central

    Lui, Clarissa; Cady, Nathaniel C.; Batt, Carl A.

    2009-01-01

    The advent of nucleic acid-based pathogen detection methods offers increased sensitivity and specificity over traditional microbiological techniques, driving the development of portable, integrated biosensors. The miniaturization and automation of integrated detection systems presents a significant advantage for rapid, portable field-based testing. In this review, we highlight current developments and directions in nucleic acid-based micro total analysis systems for the detection of bacterial pathogens. Recent progress in the miniaturization of microfluidic processing steps for cell capture, DNA extraction and purification, polymerase chain reaction, and product detection are detailed. Discussions include strategies and challenges for implementation of an integrated portable platform. PMID:22412335

  1. N-acetyl-L-cysteine affects growth, extracellular polysaccharide production, and bacterial biofilm formation on solid surfaces.

    PubMed

    Olofsson, Ann-Cathrin; Hermansson, Malte; Elwing, Hans

    2003-08-01

    N-Acetyl-L-cysteine (NAC) is used in medical treatment of patients with chronic bronchitis. The positive effects of NAC treatment have primarily been attributed to the mucus-dissolving properties of NAC, as well as its ability to decrease biofilm formation, which reduces bacterial infections. Our results suggest that NAC also may be an interesting candidate for use as an agent to reduce and prevent biofilm formation on stainless steel surfaces in environments typical of paper mill plants. Using 10 different bacterial strains isolated from a paper mill, we found that the mode of action of NAC is chemical, as well as biological, in the case of bacterial adhesion to stainless steel surfaces. The initial adhesion of bacteria is dependent on the wettability of the substratum. NAC was shown to bind to stainless steel, increasing the wettability of the surface. Moreover, NAC decreased bacterial adhesion and even detached bacteria that were adhering to stainless steel surfaces. Growth of various bacteria, as monocultures or in a multispecies community, was inhibited at different concentrations of NAC. We also found that there was no detectable degradation of extracellular polysaccharides (EPS) by NAC, indicating that NAC reduced the production of EPS, in most bacteria tested, even at concentrations at which growth was not affected. Altogether, the presence of NAC changes the texture of the biofilm formed and makes NAC an interesting candidate for use as a general inhibitor of formation of bacterial biofilms on stainless steel surfaces.

  2. A unified method to process biosolids samples for the recovery of bacterial, viral, and helminths pathogens.

    PubMed

    Alum, Absar; Rock, Channah; Abbaszadegan, Morteza

    2014-01-01

    For land application, biosolids are classified as Class A or Class B based on the levels of bacterial, viral, and helminths pathogens in residual biosolids. The current EPA methods for the detection of these groups of pathogens in biosolids include discrete steps. Therefore, a separate sample is processed independently to quantify the number of each group of the pathogens in biosolids. The aim of the study was to develop a unified method for simultaneous processing of a single biosolids sample to recover bacterial, viral, and helminths pathogens. At the first stage for developing a simultaneous method, nine eluents were compared for their efficiency to recover viruses from a 100 gm spiked biosolids sample. In the second stage, the three top performing eluents were thoroughly evaluated for the recovery of bacteria, viruses, and helminthes. For all three groups of pathogens, the glycine-based eluent provided higher recovery than the beef extract-based eluent. Additional experiments were performed to optimize performance of glycine-based eluent under various procedural factors such as, solids to eluent ratio, stir time, and centrifugation conditions. Last, the new method was directly compared with the EPA methods for the recovery of the three groups of pathogens spiked in duplicate samples of biosolids collected from different sources. For viruses, the new method yielded up to 10% higher recoveries than the EPA method. For bacteria and helminths, recoveries were 74% and 83% by the new method compared to 34% and 68% by the EPA method, respectively. The unified sample processing method significantly reduces the time required for processing biosolids samples for different groups of pathogens; it is less impacted by the intrinsic variability of samples, while providing higher yields (P = 0.05) and greater consistency than the current EPA methods.

  3. A household LOC device for online monitoring bacterial pathogens in drinking water with green design concept.

    PubMed

    Zhao, Xinyan; Dong, Tao

    2013-01-01

    Bacterial waterborne pathogens often threaten the water safety of the drinking water system. In order to protect the health of home users, a household lab-on-a-chip (LOC) device was developed for online monitoring bacterial pathogens in drinking water, which are in accord with green design concept. The chip integrated counter-flow micromixers, a T-junction droplet generator and time-delay channels (TD-Cs), which can mix water sample and reactants into droplets in air flow and incubate the droplets in the LOC for about 18 hours before observation. The detection module was simplified into a transparent observation chamber, from which the home users can evaluate the qualitative result by naked eyes. The liquid waste generated by the LOC system was sterilized and absorbed by quicklime powders. No secondary pollution was found. The preliminary test of the prototype system met its design requirements.

  4. Phage-based biomolecular filter for the capture of bacterial pathogens in liquid streams

    NASA Astrophysics Data System (ADS)

    Du, Songtao; Chen, I.-Hsuan; Horikawa, Shin; Lu, Xu; Liu, Yuzhe; Wikle, Howard C.; Suh, Sang Jin; Chin, Bryan A.

    2017-05-01

    This paper investigates a phage-based biomolecular filter that enables the evaluation of large volumes of liquids for the presence of small quantities of bacterial pathogens. The filter is a planar arrangement of phage-coated, strip-shaped magnetoelastic (ME) biosensors (4 mm × 0.8 mm × 0.03 mm), magnetically coupled to a filter frame structure, through which a liquid of interest flows. This "phage filter" is designed to capture specific bacterial pathogens and allow non-specific debris to pass, eliminating the common clogging issue in conventional bead filters. ANSYS Maxwell was used to simulate the magnetic field pattern required to hold ME biosensors densely and to optimize the frame design. Based on the simulation results, a phage filter structure was constructed, and a proof-in-concept experiment was conducted where a Salmonella solution of known concentration were passed through the filter, and the number of captured Salmonella was quantified by plate counting.

  5. Rapid, portable, multiplexed detection of bacterial pathogens directly from clinical sample matrices

    DOE PAGES

    Phaneuf, Christopher R.; Mangadu, Betty Lou Bosano; Piccini, Matthew E.; ...

    2016-09-23

    Enteric and diarrheal diseases are a major cause of childhood illness and death in countries with developing economies. Each year, more than half of a million children under the age of five die from these diseases. We have developed a portable, microfluidic platform capable of simultaneous, multiplexed detection of several of the bacterial pathogens that cause these diseases. Furthermore, this platform can perform fast, sensitive immunoassays directly from relevant, complex clinical matrices such as stool without extensive sample cleanup or preparation. Using only 1 µL of sample per assay, we demonstrate simultaneous multiplexed detection of four bacterial pathogens implicated inmore » diarrheal and enteric diseases in less than 20 min.« less

  6. Developing insights into the mechanisms of evolution of bacterial pathogens from whole-genome sequences

    PubMed Central

    Bentley, Stephen D

    2014-01-01

    Evolution of bacterial pathogen populations has been detected in a variety of ways including phenotypic tests, such as metabolic activity, reaction to antisera and drug resistance and genotypic tests that measure variation in chromosome structure, repetitive loci and individual gene sequences. While informative, these methods only capture a small subset of the total variation and, therefore, have limited resolution. Advances in sequencing technologies have made it feasible to capture whole-genome sequence variation for each sample under study, providing the potential to detect all changes at all positions in the genome from single nucleotide changes to large-scale insertions and deletions. In this review, we focus on recent work that has applied this powerful new approach and summarize some of the advances that this has brought in our understanding of the details of how bacterial pathogens evolve. PMID:23075447

  7. Label-Free Detection and Discrimination of Bacterial Pathogens Based on Hemin Recognition.

    PubMed

    Maltais, Thora R; Adak, Avijit K; Younis, Waleed; Seleem, Mohamed N; Wei, Alexander

    2016-07-20

    Hemin linked to hexa(ethylene glycol)bishydrazide was patterned by inkjet printing into periodic microarrays, and evaluated for their ability to capture bacterial pathogens expressing various hemin receptors. Bacterial adhesion was imaged under darkfield conditions with Fourier analysis, supporting a label-free method of pathogen detection. Hemin microarrays were screened against a panel of 16 bacteria and found capable of capturing multiple species, some with limits of detection as low as 10(3) cfu/mL. Several Gram-positive strains including Staphylococcus aureus and Bacillus anthracis also exhibited rapid adhesion, enabling pattern recognition within minutes of exposure. This can be attributed to differences in hemin acquisition systems: aggressively adherent bacteria express cell-surface hemin receptors (CSHRs) that enable direct hemin binding and uptake, whereas other types of bacteria including most Gram-negative strains rely on the secretion and recapture of soluble proteins (hemophores) for hemin acquisition, with consequently longer times for ligand binding and detection.

  8. [Advance on the pathogenicity and immunological application of bacterial flagella--a review].

    PubMed

    Guo, Zhiyan; Zhou, Mingxu; Duan, Qiangde; Zhu, Guoqiang

    2014-03-04

    Being a surface structure of bacteria, flagella have been thought to simply act as the locomotive organelles for a long time. In recent years, as increasing information gathered from studies on the pathogenicity of flagella, we found flagella could contribute to invasion and adhesion to the host cells, playing an important role in the biofilm formation and being correlated with bacterial virulence secretion system. Binding of flagellin and toll-like receptor 5 may stimulate signaling pathway, resulting in the pro-inflammatory response. Meanwhile, flagella act as a new immune adjuvant as well, because of their good immunity character. This article summarizes the current knowledge of bacterial flagella, including their structure, contribution to the pathogenicity of the bacteria, and their potential application in immunity.

  9. Daily variations in pathogenic bacterial populations in a monsoon influenced tropical environment.

    PubMed

    Khandeparker, Lidita; Anil, Arga Chandrashekar; Naik, Sneha D; Gaonkar, Chetan C

    2015-07-15

    Changing climatic conditions have influenced the monsoon pattern in recent years. Variations in bacterial population in one such tropical environment were observed everyday over two years and point out intra and inter annual changes driven by the intensity of rainfall. Vibrio spp. were abundant during the monsoon and so were faecal coliforms. Vibrio alginolyticus were negatively influenced by nitrate, whereas, silicate and rainfall positively influenced Vibrio parahaemolyticus numbers. It is also known that pathogenic bacteria are associated with the plankton. Changes in the abundance of plankton, which are governed mainly by environmental changes, could be responsible for variation in pathogenic bacterial abundance during monsoon, other than the land runoff due to precipitation and influx of fresh water.

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

    PubMed

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

    2013-11-01

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

  11. Nested PCR Assay for Eight Pathogens: A Rapid Tool for Diagnosis of Bacterial Meningitis.

    PubMed

    Bhagchandani, Sharda P; Kubade, Sushant; Nikhare, Priyanka P; Manke, Sonali; Chandak, Nitin H; Kabra, Dinesh; Baheti, Neeraj N; Agrawal, Vijay S; Sarda, Pankaj; Mahajan, Parikshit; Ganjre, Ashish; Purohit, Hemant J; Singh, Lokendra; Taori, Girdhar M; Daginawala, Hatim F; Kashyap, Rajpal S

    2016-02-01

    Bacterial meningitis is a dreadful infectious disease with a high mortality and morbidity if remained undiagnosed. Traditional diagnostic methods for bacterial meningitis pose a challenge in accurate identification of pathogen, making prognosis difficult. The present study is therefore aimed to design and evaluate a specific and sensitive nested 16S rDNA genus-based polymerase chain reaction (PCR) assay using clinical cerebrospinal fluid (CSF) for rapid diagnosis of eight pathogens causing the disease. The present work was dedicated to development of an in-house genus specific 16S rDNA nested PCR covering pathogens of eight genera responsible for causing bacterial meningitis using newly designed as well as literature based primers for respective genus. A total 150 suspected meningitis CSF obtained from the patients admitted to Central India Institute of Medical Sciences (CIIMS), India during the period from August 2011 to May 2014, were used to evaluate clinical sensitivity and clinical specificity of optimized PCR assays. The analytical sensitivity and specificity of our newly designed genus-specific 16S rDNA PCR were found to be ≥92%. With such a high sensitivity and specificity, our in-house nested PCR was able to give 100% sensitivity in clinically confirmed positive cases and 100% specificity in clinically confirmed negative cases indicating its applicability in clinical diagnosis. Our in-house nested PCR system therefore can diagnose the accurate pathogen causing bacterial meningitis and therefore be useful in selecting a specific treatment line to minimize morbidity. Results are obtained within 24 h and high sensitivity makes this nested PCR assay a rapid and accurate diagnostic tool compared to traditional culture-based methods.

  12. Intestinal bacterial overgrowth includes potential pathogens in the carbohydrate overload models of equine acute laminitis.

    PubMed

    Onishi, Janet C; Park, Joong-Wook; Prado, Julio; Eades, Susan C; Mirza, Mustajab H; Fugaro, Michael N; Häggblom, Max M; Reinemeyer, Craig R

    2012-10-12

    Carbohydrate overload models of equine acute laminitis are used to study the development of lameness. It is hypothesized that a diet-induced shift in cecal bacterial communities contributes to the development of the pro-inflammatory state that progresses to laminar failure. It is proposed that vasoactive amines, protease activators and endotoxin, all bacterial derived bioactive metabolites, play a role in disease development. Questions regarding the oral bioavailability of many of the bacterial derived bioactive metabolites remain. This study evaluates the possibility that a carbohydrate-induced overgrowth of potentially pathogenic cecal bacteria occurs and that bacterial translocation contributes toward the development of the pro-inflammatory state. Two groups of mixed-breed horses were used, those with laminitis induced by cornstarch (n=6) or oligofructan (n=6) and non-laminitic controls (n=8). Cecal fluid and tissue homogenates of extra-intestinal sites including the laminae were used to enumerate Gram-negative and -positive bacteria. Horses that developed Obel grade2 lameness, revealed a significant overgrowth of potentially pathogenic Gram-positive and Gram-negative intestinal bacteria within the cecal fluid. Although colonization of extra-intestinal sites with potentially pathogenic bacteria was not detected, results of this study indicate that cecal/colonic lymphadenopathy and eosinophilia develop in horses progressing to lameness. It is hypothesized that the pro-inflammatory state in carbohydrate overload models of equine acute laminitis is driven by an immune response to the rapid overgrowth of Gram-positive and Gram-negative cecal bacterial communities in the gut. Further equine research is indicated to study the immunological response, involving the lymphatic system that develops in the model.

  13. Associations between vaginal pathogenic community and bacterial vaginosis in Chinese reproductive-age women.

    PubMed

    Ling, Zongxin; Liu, Xia; Luo, Yueqiu; Wu, Xiaoxing; Yuan, Li; Tong, Xiaojuan; Li, Lanjuan; Xiang, Charlie

    2013-01-01

    Bacterial vaginosis (BV) is one of the most common urogenital infections among women of reproductive age that represents shifts in microbiota from Lactobacillus spp. to diverse anaerobes. The aim of our study was to evalute the diagnostic values of Gardnerella, Atopobium, Eggerthella, Megasphaera typeI, Leptotrichia/Sneathia and Prevotella, defined as a vaginal pathogenic community for BV and their associations with vaginal pH and Nugent scores. We investigated the vaginal pathogenic bacteria and Lactobacillus spp. with species-specific real-time quantitative PCR (qPCR) in 50 BV-positive and 50 BV-negative Chinese women of reproductive age. Relative to BV-negative subjects, a siginificant decline in Lactobacillus and an obvious increase in bacteria in the vaginal pathogenic community were observed in BV-postive subjects (P<0.05). With the exception of Megasphaera typeI, other vaginal pathogenic bacteria were highly predictable for BV with a better sensitivity and specificity. The vaginal pathogenic community was positively associated with vaginal pH and Nugent scores, while Lactobacillus spp., such as L. iners and L. crispatus was negatively associated with them (P<0.05). Our data implied that the prevalance of vaginal pathogenic bacteria as well as the depletion of Lactobacillus was highly accurate for BV diagnosis. Vaginal microbiota shifts, especially the overgrowth of the vaginal pathogenic community, showed well diagnostic values in predicting BV. Postive correlations between those vaginal pathogenic bacteria and vaginal pH, Nugent score indicated the vaginal pathogenic community rather than a single vaginal microorganism, was participated in the onset of BV directly.

  14. Associations between Vaginal Pathogenic Community and Bacterial Vaginosis in Chinese Reproductive-Age Women

    PubMed Central

    Luo, Yueqiu; Wu, Xiaoxing; Yuan, Li; Tong, Xiaojuan; Li, Lanjuan; Xiang, Charlie

    2013-01-01

    Background Bacterial vaginosis (BV) is one of the most common urogenital infections among women of reproductive age that represents shifts in microbiota from Lactobacillus spp. to diverse anaerobes. The aim of our study was to evalute the diagnostic values of Gardnerella, Atopobium, Eggerthella, Megasphaera typeI, Leptotrichia/Sneathia and Prevotella, defined as a vaginal pathogenic community for BV and their associations with vaginal pH and Nugent scores. Methods and Findings We investigated the vaginal pathogenic bacteria and Lactobacillus spp. with species-specific real-time quantitative PCR (qPCR) in 50 BV-positive and 50 BV-negative Chinese women of reproductive age. Relative to BV-negative subjects, a siginificant decline in Lactobacillus and an obvious increase in bacteria in the vaginal pathogenic community were observed in BV-postive subjects (P<0.05). With the exception of Megasphaera typeI, other vaginal pathogenic bacteria were highly predictable for BV with a better sensitivity and specificity. The vaginal pathogenic community was positively associated with vaginal pH and Nugent scores, while Lactobacillus spp., such as L. iners and L. crispatus was negatively associated with them (P<0.05). Conclusions Our data implied that the prevalance of vaginal pathogenic bacteria as well as the depletion of Lactobacillus was highly accurate for BV diagnosis. Vaginal microbiota shifts, especially the overgrowth of the vaginal pathogenic community, showed well diagnostic values in predicting BV. Postive correlations between those vaginal pathogenic bacteria and vaginal pH, Nugent score indicated the vaginal pathogenic community rather than a single vaginal microorganism, was participated in the onset of BV directly. PMID:24124575

  15. Atypical sensors for direct and rapid neuronal detection of bacterial pathogens.

    PubMed

    Lim, Ji Yeon; Choi, Seung-In; Choi, Geunyeol; Hwang, Sun Wook

    2016-03-09

    Bacterial infection can threaten the normal biological functions of a host, often leading to a disease. Hosts have developed complex immune systems to cope with the danger. Preceding the elimination of pathogens, selective recognition of the non-self invaders is necessary. At the forefront of the body's defenses are the innate immune cells, which are equipped with particular sensor molecules that can detect common exterior patterns of invading pathogens and their secreting toxins as well as with phagocytic machinery. Inflammatory mediators and cytokines released from these innate immune cells and infected tissues can boost the inflammatory cascade and further recruit adaptive immune cells to maximize the elimination and resolution. The nervous system also seems to interact with this process, mostly known to be affected by the inflammatory mediators through the binding of neuronal receptors, consequently activating neural circuits that tune the local and systemic inflammatory states. Recent research has suggested new contact points: direct interactions of sensory neurons with pathogens. Latest findings demonstrated that the sensory neurons not only share pattern recognition mechanisms with innate immune cells, but also utilize endogenous and exogenous electrogenic components for bacterial pathogen detection, by which the electrical firing prompts faster information flow than what could be achieved when the immune system is solely involved. As a result, rapid pain generation and active accommodation of the immune status occur. Here we introduced the sensory neuron-specific detector molecules for directly responding to bacterial pathogens and their signaling mechanisms. We also discussed extended issues that need to be explored in the future.

  16. Ethnomedicinal Cichorium intybus Seed Extracts: An Impending Preparation against Multidrug Resistant Bacterial Pathogens

    PubMed Central

    Rahman, Hazir; Khan, Usman Ali; Qasim, Muhammad; Muhammad, Noor; Khan, Muhammad Daud; Asif, Muhammad; Azizullah, Azizullah; Adnan, Muhammad; Murad, Waheed

    2016-01-01

    Background The present study was undertaken to analyze the phytochemical content and biological activity of Cichorium intybus seeds traditionally used in Charsadda, Pakistan against multidrug resistant (MDR) bacterial pathogens. Objectives This study explored the qualitative and quantitative antibacterial potential of C. intybus. Further qualitative analysis of phytochemical content was performed. Methods Cichorium intybus seed extracts were prepared in aqueous, chloroform, ethanol, and hexane separately. Results All the extracts of C. intybus seeds were screened for antibacterial activity and phytochemical content. Cichorium intybus seed extract showed considerable activity against MDR pathogenic bacteria. In the well diffusion method, aqueous extracts showed a higher zone of inhibition against Pseudomonas aeruginosa (16 mm ± 0.7 mm) and Acinetobacter baumannii (13 mm ± 0.5 mm), whereas chloroform, ethanol, and hexane extracts showed activity against P. aeruginosa (11 mm ± 0.3 mm, 12 mm ± 0.5 mm, and 11 mm ± 0 mm, respectively) as compared to Imipenem, a broad spectrum antibiotic. Minimum inhibitory concentration and minimum bactericidal concentration values for aqueous and ethanol extracts indicate that they were more effective against MDR bacteria. Phytochemical analysis revealed that aqueous and ethanol extracts were rich in alkaloids, carbohydrates, gallotannins, and triterpenoids, whereas chloroform and hexane extracts were more concentrated with phenolics, pseudotannins, saponins, and tannins. Cichorium intybus seed extract demonstrated potential activity against MDR human pathogenic bacteria. Conclusions The undertaken study has for the first time reported the effects of C. intybus seed extracts against MDR bacterial pathogens. Findings of the current study will be helpful for further elucidation of bioactive molecules for therapeutic use against MDR bacterial pathogens. PMID:28138372

  17. Bacteriocin from Bacillus subtilis as a novel drug against diabetic foot ulcer bacterial pathogens

    PubMed Central

    Joseph, Baby; Dhas, Berlina; Hena, Vimalin; Raj, Justin

    2013-01-01

    Objective To isolate and identify Bacillus subtilis (B. subtilis) from soil and to characterize and partially purify the bacteriocin. To evaluate the antimicrobial activity against four diabetic foot ulcer bacterial pathogens. Methods Genotypic identification was done based on Bergey's manual of systemic bacteriology. Antimicrobial susceptibility test was done by Kirby-Bauer disc diffusion method. Colonies were identified by colony morphology and biochemical characterization and also compared with MTCC 121 strain. Further identification was done by 16S rRNA sequencing. Inhibitory activities of partially purified bacteriocin on all the DFU isolates were done by agar well diffusion method. The strain was identified to produce bacteriocin by stab overlay assay. Bacteriocin was extracted by organic solvent extraction using chloroform, further purified by HPLC and physical, and chemical characterization was performed. Results The four isolates showed high level of resistance to amoxyclav and sensitivity to ciprofloxacin. HPLC purification revealed that the extracts are bacteriocin. The phylogenetic tree analysis results showed that the isolate was 99% related to B. subtilis BSF01. The results reveled activity to all the four isolates and high level of activity was seen in case of Klebsiella sp. Conclusions Partially purified bacteriocin was found to have antimicrobial activity against the four diabetic foot ulcer bacterial pathogens, which can thus be applied as a better drug molecule on further studies. The strain B. subtilis are found to be safe for use and these antimicrobial peptides can be used as an antimicrobial in humans to treat DFU bacterial pathogens. PMID:24093784

  18. General and specialized media routinely employed for primary isolation of bacterial pathogens of fishes

    USGS Publications Warehouse

    Starliper, C.E.

    2008-01-01

    There are a number of significant diseases among cultured and free-ranging freshwater fishes that have a bacterial etiology; these represent a variety of gram-negative and gram-positive genera. Confirmatory diagnosis of these diseases involves primary isolation of the causative bacterium on bacteriologic media. Frequently used "general" bacteriologic media simply provide the essential nutrients for growth. For most of the major pathogens, however, there are differential and/or selective media that facilitate primary recovery. Some specialized media are available as "ready-to-use" from suppliers, while others must be prepared. Differential media employ various types of indicator systems, such as pH indicators, that allow diagnosticians to observe assimilation of selected substrates. An advantage to the use of differential media for primary isolation is that they hasten bacterial characterization by yielding the appropriate positive or negative result for a particular substrate, often leading to a presumptive identification. Selective media also incorporate agent(s) that inhibit the growth of contaminants typically encountered with samples from aquatic environments. Media that incorporate differential and/or selective components are ideally based on characters that are unique to the targeted bacterium, and their use can reduce the time associated with diagnosis and facilitate early intervention in affected fish populations. In this review, the concepts of general and differential/selective bacteriologic media and their use and development for fish pathogens are discussed. The media routinely employed for primary isolation of the significant bacterial pathogens of fishes are presented. ?? Wildlife Disease Association 2008.

  19. Exposure to viral and bacterial pathogens among Soay sheep (Ovis aries) of the St Kilda archipelago.

    PubMed

    Graham, A L; Nussey, D H; Lloyd-Smith, J O; Longbottom, D; Maley, M; Pemberton, J M; Pilkington, J G; Prager, K C; Smith, L; Watt, K A; Wilson, K; McNEILLY, T N; Brülisauer, F

    2016-07-01

    We assessed evidence of exposure to viruses and bacteria in an unmanaged and long-isolated population of Soay sheep (Ovis aries) inhabiting Hirta, in the St Kilda archipelago, 65 km west of Benbecula in the Outer Hebrides of Scotland. The sheep harbour many metazoan and protozoan parasites but their exposure to viral and bacterial pathogens is unknown. We tested for herpes viral DNA in leucocytes and found that 21 of 42 tested sheep were infected with ovine herpesvirus 2 (OHV-2). We also tested 750 plasma samples collected between 1997 and 2010 for evidence of exposure to seven other viral and bacterial agents common in domestic Scottish sheep. We found evidence of exposure to Leptospira spp., with overall seroprevalence of 6·5%. However, serological evidence indicated that the population had not been exposed to border disease, parainfluenza, maedi-visna, or orf viruses, nor to Chlamydia abortus. Some sheep tested positive for antibodies against Mycobacterium avium subsp. paratuberculosis (MAP) but, in the absence of retrospective faecal samples, the presence of this infection could not be confirmed. The roles of importation, the pathogen-host interaction, nematode co-infection and local transmission warrant future investigation, to elucidate the transmission ecology and fitness effects of the few viral and bacterial pathogens on Hirta.

  20. Gene Loss Dominates As a Source of Genetic Variation within Clonal Pathogenic Bacterial Species.

    PubMed

    Bolotin, Evgeni; Hershberg, Ruth

    2015-07-10

    Some of the most dangerous pathogens such as Mycobacterium tuberculosis and Yersinia pestis evolve clonally. This means that little or no recombination occurs between strains belonging to these species. Paradoxically, although different members of these species show extreme sequence similarity of orthologous genes, some show considerable intraspecies phenotypic variation, the source of which remains elusive. To examine the possible sources of phenotypic variation within clonal pathogenic bacterial species, we carried out an extensive genomic and pan-genomic analysis of the sources of genetic variation available to a large collection of clonal and nonclonal pathogenic bacterial species. We show that while nonclonal species diversify through a combination of changes to gene sequences, gene loss and gene gain, gene loss completely dominates as a source of genetic variation within clonal species. Indeed, gene loss is so prevalent within clonal species as to lead to levels of gene content variation comparable to those found in some nonclonal species that are much more diverged in their gene sequences and that acquire a substantial number of genes horizontally. Gene loss therefore needs to be taken into account as a potential dominant source of phenotypic variation within clonal bacterial species.

  1. Rapid single-colony whole-genome sequencing of bacterial pathogens

    PubMed Central

    Köser, Claudio U.; Fraser, Louise J.; Ioannou, Avgousta; Becq, Jennifer; Ellington, Matthew J.; Holden, Matthew T. G.; Reuter, Sandra; Török, M. Estée; Bentley, Stephen D.; Parkhill, Julian; Gormley, Niall A.; Smith, Geoffrey P.; Peacock, Sharon J.

    2014-01-01

    Objectives As a result of the introduction of rapid benchtop sequencers, the time required to subculture a bacterial pathogen to extract sufficient DNA for library preparation can now exceed the time to sequence said DNA. We have eliminated this rate-limiting step by developing a protocol to generate DNA libraries for whole-genome sequencing directly from single bacterial colonies grown on primary culture plates. Methods We developed our protocol using single colonies of 17 bacterial pathogens responsible for severe human infection that were grown using standard diagnostic media and incubation conditions. We then applied this method to four clinical scenarios that currently require time-consuming reference laboratory tests: full identification and genotyping of salmonellae; identification of blaNDM-1, a highly transmissible carbapenemase resistance gene, in Klebsiella pneumoniae; detection of genes encoding staphylococcal toxins associated with specific disease syndromes; and monitoring of vaccine targets to detect vaccine escape in Neisseria meningitidis. Results We validated our single-colony whole-genome sequencing protocol for all 40 combinations of pathogen and selective, non-selective or indicator media tested in this study. Moreover, we demonstrated the clinical value of this method compared with current reference laboratory tests. Conclusions This advance will facilitate the implementation of whole-genome sequencing into diagnostic and public health microbiology. PMID:24370932

  2. Electrochemical Biosensor for Rapid and Sensitive Detection of Magnetically Extracted Bacterial Pathogens

    PubMed Central

    Setterington, Emma B.; Alocilja, Evangelyn C.

    2012-01-01

    Biological defense and security applications demand rapid, sensitive detection of bacterial pathogens. This work presents a novel qualitative electrochemical detection technique which is applied to two representative bacterial pathogens, Bacillus cereus (as a surrogate for B. anthracis) and Escherichia coli O157:H7, resulting in detection limits of 40 CFU/mL and 6 CFU/mL, respectively, from pure culture. Cyclic voltammetry is combined with immunomagnetic separation in a rapid method requiring approximately 1 h for presumptive positive/negative results. An immunofunctionalized magnetic/polyaniline core/shell nano-particle (c/sNP) is employed to extract target cells from the sample solution and magnetically position them on a screen-printed carbon electrode (SPCE) sensor. The presence of target cells significantly inhibits current flow between the electrically active c/sNPs and SPCE. This method has the potential to be adapted for a wide variety of target organisms and sample matrices, and to become a fully portable system for routine monitoring or emergency detection of bacterial pathogens. PMID:25585629

  3. Well-known surface and extracellular antigens of pathogenic microorganisms among the immunodominant proteins of the infectious microalgae Prototheca zopfii

    PubMed Central

    Irrgang, Alexandra; Murugaiyan, Jayaseelan; Weise, Christoph; Azab, Walid; Roesler, Uwe

    2015-01-01

    Microalgae of the genus Prototheca (P.) are associated with rare but severe infections (protothecosis) and represent a potential zoonotic risk. Genotype (GT) 2 of P. zopfii has been established as pathogenic agent for humans, dogs, and cattle, whereas GT1 is considered to be non-pathogenic. Since pathogenesis is poorly understood, the aim of this study was to determine immunogenic proteins and potential virulence factors of P. zopfii GT2. Therefore, 2D western blot analyses with sera and isolates of two dogs naturally infected with P. zopfii GT2 have been performed. Cross-reactivity was determined by including the type strains of P. zopfii GT2, P. zopfii GT1, and P. blaschkeae, a close relative of P. zopfii, which is known to cause subclinical forms of bovine mastitis. The sera showed a high strain-, genotype-, and species-cross-reactivity. A total of 198 immunogenic proteins have been analyzed via MALDI—TOF MS. The majority of the 86 identified proteins are intracellularly located (e.g., malate dehydrogenase, oxidoreductase, 3-dehydroquinate synthase) but some antigens and potential virulence factors, known from other pathogens, have been found (e.g., phosphomannomutase, triosephosphate isomerase). One genotype-specific antigen could be identified as heat shock protein 70 (Hsp70), a well-known antigen of eukaryotic pathogens with immunological importance when located extracellularly. Both sera were reactive to glyceraldehyde-3-phosphate-dehydrogenase of all investigated strains. This house-keeping enzyme is found to be located on the surface of several pathogens as virulence factor. Flow-cytometric analysis revealed its presence on the surface of P. blaschkeae. PMID:26484314

  4. Chemical communication in the gut: Effects of microbiota-generated metabolites on gastrointestinal bacterial pathogens.

    PubMed

    Vogt, Stefanie L; Peña-Díaz, Jorge; Finlay, B Brett

    2015-08-01

    Gastrointestinal pathogens must overcome many obstacles in order to successfully colonize a host, not the least of which is the presence of the gut microbiota, the trillions of commensal microorganisms inhabiting mammals' digestive tracts, and their products. It is well established that a healthy gut microbiota provides its host with protection from numerous pathogens, including Salmonella species, Clostridium difficile, diarrheagenic Escherichia coli, and Vibrio cholerae. Conversely, pathogenic bacteria have evolved mechanisms to establish an infection and thrive in the face of fierce competition from the microbiota for space and nutrients. Here, we review the evidence that gut microbiota-generated metabolites play a key role in determining the outcome of infection by bacterial pathogens. By consuming and transforming dietary and host-produced metabolites, as well as secreting primary and secondary metabolites of their own, the microbiota define the chemical environment of the gut and often determine specific host responses. Although most gut microbiota-produced metabolites are currently uncharacterized, several well-studied molecules made or modified by the microbiota are known to affect the growth and virulence of pathogens, including short-chain fatty acids, succinate, mucin O-glycans, molecular hydrogen, secondary bile acids, and the AI-2 quorum sensing autoinducer. We also discuss challenges and possible approaches to further study of the chemical interplay between microbiota and gastrointestinal pathogens.

  5. Parasites and competitors suppress bacterial pathogen synergistically due to evolutionary trade‐offs

    PubMed Central

    Wang, Xiaofang; Wei, Zhong; Li, Mei; Wang, Xueqi; Shan, Anqi; Mei, Xinlan; Jousset, Alexandre; Shen, Qirong; Xu, Yangchun; Friman, Ville‐Petri

    2016-01-01

    Parasites and competitors are important for regulating pathogen densities and subsequent disease dynamics. It is, however, unclear to what extent this is driven by ecological and evolutionary processes. Here, we used experimental evolution to study the eco‐evolutionary feedbacks among Ralstonia solanacearum bacterial pathogen, Ralstonia‐specific phage parasite, and Bacillus amyloliquefaciens competitor bacterium in the laboratory and plant rhizosphere. We found that while the phage had a small effect on pathogen densities on its own, it considerably increased the R. solanacearum sensitivity to antibiotics produced by B. amyloliquefaciens. Instead of density effects, this synergy was due to phage‐driven increase in phage resistance that led to trade‐off with the resistance to B. amyloliquefaciens antibiotics. While no evidence was found for pathogen resistance evolution to B. amyloliquefaciens antibiotics, the fitness cost of adaptation (reduced growth) was highest when the pathogen had evolved in the presence of both parasite and competitor. Qualitatively similar patterns were found between laboratory and greenhouse experiments even though the evolution of phage resistance was considerably attenuated in the tomato rhizosphere. These results suggest that evolutionary trade‐offs can impose strong constraints on disease dynamics and that combining phages and antibiotic‐producing bacteria could be an efficient way to control agricultural pathogens. PMID:27925169

  6. Parasites and competitors suppress bacterial pathogen synergistically due to evolutionary trade-offs.

    PubMed

    Wang, Xiaofang; Wei, Zhong; Li, Mei; Wang, Xueqi; Shan, Anqi; Mei, Xinlan; Jousset, Alexandre; Shen, Qirong; Xu, Yangchun; Friman, Ville-Petri

    2016-12-07

    Parasites and competitors are important for regulating pathogen densities and subsequent disease dynamics. It is, however, unclear to what extent this is driven by ecological and evolutionary processes. Here, we used experimental evolution to study the eco-evolutionary feedbacks among Ralstonia solanacearum bacterial pathogen, Ralstonia-specific phage parasite, and Bacillus amyloliquefaciens competitor bacterium in the laboratory and plant rhizosphere. We found that while the phage had a small effect on pathogen densities on its own, it considerably increased the R. solanacearum sensitivity to antibiotics produced by B. amyloliquefaciens. Instead of density effects, this synergy was due to phage-driven increase in phage resistance that led to trade-off with the resistance to B. amyloliquefaciens antibiotics. While no evidence was found for pathogen resistance evolution to B. amyloliquefaciens antibiotics, the fitness cost of adaptation (reduced growth) was highest when the pathogen had evolved in the presence of both parasite and competitor. Qualitatively similar patterns were found between laboratory and greenhouse experiments even though the evolution of phage resistance was considerably attenuated in the tomato rhizosphere. These results suggest that evolutionary trade-offs can impose strong constraints on disease dynamics and that combining phages and antibiotic-producing bacteria could be an efficient way to control agricultural pathogens.

  7. Extracellular Lipase and Protease Production from a Model Drinking Water Bacterial Community Is Functionally Robust to Absence of Individual Members.

    PubMed

    Willsey, Graham G; Wargo, Matthew J

    2015-01-01

    Bacteria secrete enzymes into the extracellular space to hydrolyze macromolecules into constituents that can be imported for microbial nutrition. In bacterial communities, these enzymes and their resultant products can be modeled as community property. Our goal was to investigate the impact of individual community member absence on the resulting community production of exoenzymes (extracellular enzymes) involved in lipid and protein hydrolysis. Our model community contained nine bacteria isolated from the potable water system of the International Space Station. Bacteria were grown in static conditions individually, all together, or in all combinations of eight species and exoproduct production was measured by colorimetric or fluorometric reagents to assess short chain and long chain lipases, choline-specific phospholipases C, and proteases. The exoenzyme production of each species grown alone varied widely, however, the enzyme activity levels of the mixed communities were functionally robust to absence of any single species, with the exception of phospholipase C production in one community. For phospholipase C, absence of Chryseobacterium gleum led to increased choline-specific phospholipase C production, correlated with increased growth of Burkholderia cepacia and Sphingomonas sanguinis. Because each individual species produced different enzyme activity levels in isolation, we calculated an expected activity value for each bacterial mixture using input levels or known final composition. This analysis suggested that robustness of each exoenzyme activity is not solely mediated by community composition, but possibly influenced by bacterial communication, which is known to regulate such pathways in many bacteria. We conclude that in this simplified model of a drinking water bacterial community, community structure imposes constraints on production and/or secretion of exoenzymes to generate a level appropriate to exploit a given nutrient environment.

  8. Extracellular Lipase and Protease Production from a Model Drinking Water Bacterial Community Is Functionally Robust to Absence of Individual Members

    PubMed Central

    Willsey, Graham G.; Wargo, Matthew J.

    2015-01-01

    Bacteria secrete enzymes into the extracellular space to hydrolyze macromolecules into constituents that can be imported for microbial nutrition. In bacterial communities, these enzymes and their resultant products can be modeled as community property. Our goal was to investigate the impact of individual community member absence on the resulting community production of exoenzymes (extracellular enzymes) involved in lipid and protein hydrolysis. Our model community contained nine bacteria isolated from the potable water system of the International Space Station. Bacteria were grown in static conditions individually, all together, or in all combinations of eight species and exoproduct production was measured by colorimetric or fluorometric reagents to assess short chain and long chain lipases, choline-specific phospholipases C, and proteases. The exoenzyme production of each species grown alone varied widely, however, the enzyme activity levels of the mixed communities were functionally robust to absence of any single species, with the exception of phospholipase C production in one community. For phospholipase C, absence of Chryseobacterium gleum led to increased choline-specific phospholipase C production, correlated with increased growth of Burkholderia cepacia and Sphingomonas sanguinis. Because each individual species produced different enzyme activity levels in isolation, we calculated an expected activity value for each bacterial mixture using input levels or known final composition. This analysis suggested that robustness of each exoenzyme activity is not solely mediated by community composition, but possibly influenced by bacterial communication, which is known to regulate such pathways in many bacteria. We conclude that in this simplified model of a drinking water bacterial community, community structure imposes constraints on production and/or secretion of exoenzymes to generate a level appropriate to exploit a given nutrient environment. PMID:26599415

  9. Diet and Environment Shape Fecal Bacterial Microbiota Composition and Enteric Pathogen Load of Grizzly Bears

    PubMed Central

    Schwab, Clarissa; Cristescu, Bogdan; Northrup, Joseph M.; Stenhouse, Gordon B.; Gänzle, Michael

    2011-01-01

    Background Diet and environment impact the composition of mammalian intestinal microbiota; dietary or health disturbances trigger alterations in intestinal microbiota composition and render the host susceptible to enteric pathogens. To date no long term monitoring data exist on the fecal microbiota and pathogen load of carnivores either in natural environments or in captivity. This study investigates fecal microbiota composition and the presence of pathogenic Escherichia coli and toxigenic clostridia in wild and captive grizzly bears (Ursus arctos) and relates these to food resources consumed by bears. Methodology/Principal Findings Feces were obtained from animals of two wild populations and from two captive animals during an active bear season. Wild animals consumed a diverse diet composed of plant material, animal prey and insects. Captive animals were fed a regular granulated diet with a supplement of fruits and vegetables. Bacterial populations were analyzed using quantitative PCR. Fecal microbiota composition fluctuated in wild and in captive animals. The abundance of Clostridium clusters I and XI, and of C. perfringens correlated to regular diet protein intake. Enteroaggregative E. coli were consistently present in all populations. The C. sordellii phospholipase C was identified in three samples of wild animals and for the first time in Ursids. Conclusion This is the first longitudinal study monitoring the fecal microbiota of wild carnivores and comparing it to that of captive individuals of the same species. Location and diet affected fecal bacterial populations as well as the presence of enteric pathogens. PMID:22194798

  10. Parasitic, bacterial and viral pathogens isolated from diarrhoeal and routine stool specimens of urban Bangladeshi children.

    PubMed

    Stanton, B; Silimperi, D R; Khatun, K; Kay, B; Ahmed, S; Khatun, J; Alam, K

    1989-02-01

    Few data exist in Bangladesh on longitudinal, community-based studies of bacterial or parasitic pathogens identified in routine and diarrhoeal stools of urban dwelling children. We undertook the following study on 343 children of age less than 6 years who resided in one of 51 slum settings in Dhaka, Bangladesh, between October 1984 and February 1986. Specimens from diarrhoeal episodes and from routine stools obtained at 3-monthly intervals were examined for parasites, rotavirus and pathogenic bacteria. Parasites were isolated from 509 (51%) of the 1006 routine stools and from 95 (42%) of the 225 diarrhoeal stools. Isolation rates steadily increased with age. Ascaris lumbricoides and Trichuris trichiura accounted for approximately 80% of all parasitic isolates in routine and diarrhoeal stools. Giardia lamblia was isolated from 11% diarrhoeal stools. Entamoeba histolytica was an uncommon isolate (less than 1%). Bacterial pathogens were identified in 55 (24%) of the diarrhoeal stools but were identified in only 164 (16%) of the 1028 routine stools examined (P less than 0.01). Toxigenic Escherichia coli, Shigellae and Campylobacter were the most frequent isolates from diarrhoeal and routine specimens. This pathogen profile appears to be more in keeping with that from urban settings in other developing countries than from rural Bangladesh, suggesting that extrapolations from rural-based data should not be made for urban settings.

  11. Analysis of bacterial metagenomes from the Southwestern Gulf of Mexico for pathogens detection.

    PubMed

    Escobedo-Hinojosa, Wendy; Pardo-López, Liliana

    2017-07-31

    Little is known about the diversity of bacteria in the Southwestern Gulf of Mexico. The aim of the study illustrated in this perspective was to search for the presence of bacterial pathogens in this ecosystem, using metagenomic data recently generated by the Mexican research group known as the Gulf of Mexico Research Consortium. Several genera of bacteria annotated as pathogens were detected in water and sediment marine samples. As expected, native and ubiquitous pathogenic bacteria genera such as Burkolderia, Halomonas, Pseudomonas, Shewanella and Vibrio were highly represented. Surprisingly, non-native genera of public health concern were also detected, including Borrelia, Ehrlichia, Leptospira, Mycobacterium, Mycoplasma, Salmonella, Staphylococcus, Streptococcus and Treponema. While there are no previous metagenomics studies of this environment, the potential influences of natural, anthropogenic and ecological factors on the diversity of putative pathogenic bacteria found in it are reviewed. The taxonomic annotation herein reported provides a starting point for an improved understanding of bacterial biodiversity in the Southwestern Gulf of Mexico. It also represents a useful tool in public health as it may help identify infectious diseases associated with exposure to marine water and ingestion of fish or shellfish, and thus may be useful in predicting and preventing waterborne disease outbreaks. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  12. Molecular versus conventional culture for detection of respiratory bacterial pathogens in poultry.

    PubMed

    Ammar, A M; Abd El-Aziz, N K; Abd El Wanis, S; Bakry, N R

    2016-02-29

    Acute respiratory tract infections are leading causes of morbidity in poultry farms allover the world. Six pathogens; Escherichia coli, Mycoplasma gallisepticum, Staphylococcus aureus, Pasteurella multocida, Mannheimia haemolytica and Pseudomonas aeruginosa were involved in respiratory infections in poultry. Herein, conventional identification procedures and polymerase chain reaction (PCR) were applied for detection of the most common respiratory bacterial pathogens in clinical specimens of poultry obtained from 53 Egyptian farms with various respiratory problems and the results were compared statistically. The analyzed data demonstrated a significantly higher rate of detection of the most recovered microorganisms (P<0.05) by PCR comparing to classical culture procedures. Further, multiplex PCR could detect E. coli, M. gallisepticum, S. aureus and Ps. aeruginosa in a single reaction, however, M. haemolytica was reported in a uinplex system. According to PCR results, the most commonly recorded bacterial pathogens in examined poultry farms were E. coli and Ps. aeruginosa (54.71% each), followed by M. haemolylica (35.85%) and M. gallisepticum (20.75%). In conclusion, PCR assay offered an effective alternative to traditional typing methods for the identification and simultaneous detection of the most clinically relevant respiratory pathogens in poultry.

  13. Host-Directed Antimicrobial Drugs with Broad-Spectrum Efficacy against Intracellular Bacterial Pathogens

    PubMed Central

    Czyż, Daniel M.; Potluri, Lakshmi-Prasad; Jain-Gupta, Neeta; Riley, Sean P.; Martinez, Juan J.; Steck, Theodore L.; Crosson, Sean; Gabay, Joëlle E.

    2014-01-01

    ABSTRACT We sought a new approach to treating infections by intracellular bacteria, namely, by altering host cell functions that support their growth. We screened a library of 640 Food and Drug Administration (FDA)-approved compounds for agents that render THP-1 cells resistant to infection by four intracellular pathogens. We identified numerous drugs that are not antibiotics but were highly effective in inhibiting intracellular bacterial growth with limited toxicity to host cells. These compounds are likely to target three kinds of host functions: (i) G protein-coupled receptors, (ii) intracellular calcium signals, and (iii) membrane cholesterol distribution. The compounds that targeted G protein receptor signaling and calcium fluxes broadly inhibited Coxiella burnetii, Legionella pneumophila, Brucella abortus, and Rickettsia conorii, while those directed against cholesterol traffic strongly attenuated the intracellular growth of C. burnetii and L. pneumophila. These pathways probably support intracellular pathogen growth so that drugs that perturb them may be therapeutic candidates. Combining host- and pathogen-directed treatments is a strategy to decrease the emergence of drug-resistant intracellular bacterial pathogens. PMID:25073644

  14. Parasitic, bacterial, and viral enteric pathogens associated with diarrhea in the Central African Republic.

    PubMed Central

    Georges, M C; Wachsmuth, I K; Meunier, D M; Nebout, N; Didier, F; Siopathis, M R; Georges, A J

    1984-01-01

    A total of 1,197 diarrheic children less than 15 years old were investigated for parasitic, bacterial, and viral enteropathogens from March 1981 through February 1982 in the Central African Republic. One or more pathogens were identified from 49.4% of the patients. Rotavirus was the most frequently identified pathogen among children less than 18 months old. Enteropathogenic Escherichia coli was the second most frequently isolated pathogen (12.1%) in children less than 2 years of age. Campylobacter jejuni was also isolated frequently from diarrheic children less than 5 years of age (10.9%). Entamoeba histolytica was identified in very young children and was found to be the most frequent enteropathogen associated with diarrhea in children over the age of 2 years. Enterotoxigenic Escherichia coli was rarely isolated (ca. 2%). There was a peak in the incidence of rotavirus during the dry season and in the incidence of Campylobacter jejuni during the rainy season. PMID:6330161

  15. Bacterial and viral pathogens detected in sea turtles stranded along the coast of Tuscany, Italy.

    PubMed

    Fichi, G; Cardeti, G; Cersini, A; Mancusi, C; Guarducci, M; Di Guardo, G; Terracciano, G

    2016-03-15

    During 2014, six loggerhead turtles, Caretta caretta and one green turtle, Chelonia mydas, found stranded on the Tuscany coast of Italy, were examined for the presence of specific bacterial and viral agents, along with their role as carriers of fish and human pathogens. Thirteen different species of bacteria, 10 Gram negative and 3 Gram positive, were identified. Among them, two strains of Vibrio parahaemolyticus and one strain of Lactococcus garviae were recovered and confirmed by specific PCR protocols. No trh and tdh genes were detected in V. parahaemolyticus. The first isolation of L. garviae and the first detection of Betanodavirus in sea turtles indicate the possibility for sea turtles to act as carriers of fish pathogens. Furthermore, the isolation of two strains of V. parahaemolyticus highlights the possible role of these animals in human pathogens' diffusion.

  16. The RpfB-Dependent Quorum Sensing Signal Turnover System Is Required for Adaptation and Virulence in Rice Bacterial Blight Pathogen Xanthomonas oryzae pv. oryzae.

    PubMed

    Wang, Xing-Yu; Zhou, Lian; Yang, Jun; Ji, Guang-Hai; He, Ya-Wen

    2016-03-01

    Xanthomonas oryzae pv. oryzae, the bacterial blight pathogen of rice, produces diffusible signal factor (DSF) family quorum sensing signals to regulate virulence. The biosynthesis and perception of DSF family signals require components of the rpf (regulation of pathogenicity factors) cluster. In this study, we report that RpfB plays an essential role in DSF family signal turnover in X. oryzae pv. oryzae PXO99A. The production of DSF family signals was boosted by deletion of the rpfB gene and was abolished by its overexpression. The RpfC/RpfG-mediated DSF signaling system negatively regulates rpfB expression via the global transcription regulator Clp, whose activity is reversible in the presence of cyclic diguanylate monophosphate. These findings indicate that the DSF family signal turnover system in PXO99A is generally consistent with that in Xanthomonas campestris pv. campestris. Moreover, this study has revealed several specific roles of RpfB in PXO99A. First, the rpfB deletion mutant produced high levels of DSF family signals but reduced extracellular polysaccharide production, extracellular amylase activity, and attenuated pathogenicity. Second, the rpfB/rpfC double-deletion mutant was partially deficient in xanthomonadin production. Taken together, the RpfB-dependent DSF family signal turnover system is a conserved and naturally presenting signal turnover system in Xanthomonas spp., which plays unique roles in X. oryzae pv. oryzae adaptation and pathogenesis.

  17. Occurrence and antibacterial susceptibility pattern of bacterial pathogens isolated from diarrheal patients in Pakistan

    PubMed Central

    Rasool, Muhammad H.; Siddique, Abu B.; Saqalein, Muhammad; Asghar, Muhammad J.; Zahoor, Muhammad A.; Aslam, Bilal; Shafiq, Humerah B.; Nisar, Muhammad A.

    2016-01-01

    Objective: To determine the occurrence of bacterial pathogens responsible for diarrhea and to engender information regarding the effectiveness of commonly used antibiotic against diarrhea. Methods: This cross-sectional study was conducted between April and July 2014. Samples were collected from the Divisional Headquarter and Allied Hospital, Faisalabad, Pakistan. The differential and selective media were used to isolate bacterial pathogens, which were identified through cultural characteristics, microscopy, and biochemical tests. Disc diffusion assay was carried out using Muller Hinton agar medium, and minimum inhibitory concentration was determined using broth dilution method against isolated pathogens. Results: One hundred and forty-one (100%) samples were positive for some bacteria. Frequency of occurrence was Bacillus cereus (B. cereus) (66%), Escherichia coli (E. coli) (48.5%), Salmonella typhi (S. Typhi) (27.7%), Pseudomonas aeruginosa (P. aeruginosa) (8.5%), and Staphylococcus aureus (S. aureus) (4.3%). Single pathogen was detected in 20 (14.2%) samples whereas combinations were found in 121 (85.8%) samples. Bacillus cereus and E. coli were the most frequently detected pathogens followed by the S. Typhi, P. aeruginosa, and Staph. aureus. The percentage occurrence of isolated pathogens was 31% in B. cereus, 31% in E. coli, 18% in S. Typhi, 5% in P. aeruginosa, and 3% in Staph. aureus. Conclusion: Pseudomonas aeruginosa showed resistance against Amoxicillin and Cefotaxime, whereas S. aureus was found resistant against Cefotaxime. Statistical analysis using one way Analysis of Variance revealed that Ofloxacin and Gentamicin had significant (p<0.05) differences against all isolates as compared with other antibiotics used in this study. PMID:26905349

  18. Bacterial pathogens in Hawaiian coastal streams--associations with fecal indicators, land cover, and water quality.

    PubMed

    Viau, Emily J; Goodwin, Kelly D; Yamahara, Kevan M; Layton, Blythe A; Sassoubre, Lauren M; Burns, Siobhán L; Tong, Hsin-I; Wong, Simon H C; Lu, Yuanan; Boehm, Alexandria B

    2011-05-01

    This work aimed to understand the distribution of five bacterial pathogens in O'ahu coastal streams and relate their presence to microbial indicator concentrations, land cover of the surrounding watersheds, and physical-chemical measures of stream water quality. Twenty-two streams were sampled four times (in December and March, before sunrise and at high noon) to capture seasonal and time of day variation. Salmonella, Campylobacter, Staphylococcus aureus, Vibrio vulnificus, and V. parahaemolyticus were widespread -12 of 22 O'ahu streams had all five pathogens. All stream waters also had detectable concentrations of four fecal indicators and total vibrio with log mean ± standard deviation densities of 2.2 ± 0.8 enterococci, 2.7 ± 0.7 Escherichia coli, 1.1 ± 0.7 Clostridium perfringens, 1.2 ± 0.8 F(+) coliphages, and 3.6 ± 0.7 total vibrio per 100 ml. Bivariate associations between pathogens and indicators showed enterococci positively associated with the greatest number of bacterial pathogens. Higher concentrations of enterococci and higher incidence of Campylobacter were found in stream waters collected before sunrise, suggesting these organisms are sensitive to sunlight. Multivariate regression models of microbes as a function of land cover and physical-chemical water quality showed positive associations between Salmonella and agricultural and forested land covers, and between S. aureus and urban and agricultural land covers; these results suggested that sources specific to those land covers may contribute these pathogens to streams. Further, significant associations between some microbial targets and physical-chemical stream water quality (i.e., temperature, nutrients, turbidity) suggested that organism persistence may be affected by stream characteristics. Results implicate streams as a source of pathogens to coastal waters. Future work is recommended to determine infectious risks of recreational waterborne illness related to O'ahu stream exposures and to

  19. Infection Strategies of Bacterial and Viral Pathogens through Pathogen–Human Protein–Protein Interactions

    PubMed Central

    Durmuş Tekir, Saliha; Çakir, Tunahan; Ülgen, Kutlu Ö

    2012-01-01

    Since ancient times, even in today’s modern world, infectious diseases cause lots of people to die. Infectious organisms, pathogens, cause diseases by physical interactions with human proteins. A thorough analysis of these interspecies interactions is required to provide insights about infection strategies of pathogens. Here we analyzed the most comprehensive available pathogen–human protein interaction data including 23,435 interactions, targeting 5,210 human proteins. The data were obtained from the newly developed pathogen–host interaction search tool, PHISTO. This is the first comprehensive attempt to get a comparison between bacterial and viral infections. We investigated human proteins that are targeted by bacteria and viruses to provide an overview of common and special infection strategies used by these pathogen types. We observed that in the human protein interaction network the proteins targeted by pathogens have higher connectivity and betweenness centrality values than those proteins not interacting with pathogens. The preference of interacting with hub and bottleneck proteins is found to be a common infection strategy of all types of pathogens to manipulate essential mechanisms in human. Compared to bacteria, viruses tend to interact with human proteins of much higher connectivity and centrality values in the human network. Gene Ontology enrichment analysis of the human proteins targeted by pathogens indicates crucial clues about the infection mechanisms of bacteria and viruses. As the main infection strategy, bacteria interact with human proteins that function in immune response to disrupt human defense mechanisms. Indispensable viral strategy, on the other hand, is the manipulation of human cellular processes in order to use that transcriptional machinery for their own genetic material transcription. A novel observation about pathogen–human systems is that the human proteins targeted by both pathogens are enriched in the regulation of

  20. Modeling interactions of toxic metals with suspended bacterial cells, extracellular polymer and biofilms in a simulated freshwater environment

    SciTech Connect

    Nelson, Y.M.; Lo, W.; Lion, L.W.

    1995-12-01

    The transport of transition metals in aquatic environments is governed by their interactions with suspended and adherent biological materials and with colloidal and deposited metal oxides. These interactions were investigated using a laboratory biofilm reactor system containing a pure culture of a single bacterial species (Pseudomonas cepacia) to exemplify biological factors influencing trace metals. Use of controlled conditions allowed for development of mechanistic models to describe bacterial growth and attachment, extracellular polymer production, and biofilm accumulation as well as the interactions of each of these phases with trace metals (exemplified by lead). Lead binding to each component of the system was characterized by determining adsorption isotherms in separate experiments. Integration of the biological model with lead binding data and a chemical equilibrium program (MINEQL) to determine speciation provided a general mechanistic model to predict lead transport and distribution. The most significant factors influencing lead distribution in these experiments were lead binding to biofilms, which consisted of up to 80% extracellular polymer and lead binding to iron oxide deposits.

  1. Decay of genetic markers for fecal bacterial indicators and pathogens in sand from Lake Superior.

    PubMed

    Eichmiller, Jessica J; Borchert, Andrew J; Sadowsky, Michael J; Hicks, Randall E

    2014-08-01

    Beach sands impact water quality and pathogen loads, however, the comparative decay of the fecal indicator bacteria (FIB) Enterococcus spp. and Escherichia coli, and pathogens in freshwater sand have not been examined. In this study, freshwater sand microcosms were inoculated with sewage and pure cultures of bacterial pathogens to compare relative decay rates. The abundance of culturable Enterococcus spp. and E. coli, genetic markers for Enterococcus spp. (Entero1), total Bacteroides (AllBac), and human-specific Bacteroides (HF183), and genetic markers for the pathogens Campylobacter jejuni, methicillin-resistant Staphylococcus aureus (MRSA), Salmonella enterica subsp. enterica serovar Typhimurium, and Shigella flexneri were monitored over the course of two weeks using conventional culture methods and quantitative PCR (qPCR). The effect of moisture on the persistence of culturable FIB and all genetic markers was also determined. In addition, propidium monoazide (PMA) treatment was used to examine differences in the persistence of total genetic markers and those from live cells. Decay rates were statistically compared using Tukey's test. Moisture had a significant (p ≤ 0.05) effect on the decay rates of culturable indicator bacteria, total AllBac markers, and genetic markers for FIB, Salmonella, and MRSA from live cells. At 14% sand moisture, the decay rate of total markers was slower than that of live cells for all qPCR assays, but at 28% moisture, there was no difference in the decay rates of total and live markers for any assay. AllBac and MRSA markers increased in sand at 28% moisture, probably indicating cellular growth. Overall, culturable FIB and HF183 had decay rates that were most comparable to the bacterial pathogen markers examined in this study, whereas Entero1 and AllBac rarely exhibited decay rates similar to the bacterial pathogens in this study. The choice of FIB for assessment of fecal contamination in freshwater sand should take into account

  2. Bacterial biofilm-based catheter-associated urinary tract infections: Causative pathogens and antibiotic resistance.

    PubMed

    Sabir, Nargis; Ikram, Aamer; Zaman, Gohar; Satti, Luqman; Gardezi, Adeel; Ahmed, Abeera; Ahmed, Parvez

    2017-10-01

    We sought to determine the incidence of bacterial biofilm-based catheter-associated urinary tract infections, identify variables affecting biofilm formation, and identify etiologic bacterial pathogens and antibiotic-resistance patterns associated with biofilm-based catheter-associated urinary tract infections (CAUTIs) in our setup. Patients who developed at least 2 symptoms of urinary tract infection after at least 2 days of indwelling urinary catheters were included. Urine was collected aseptically from catheter tubing and processed per standard microbiologic practices. Bacterial pathogens were identified on the basis of gram staining, colony morphology, and biochemical reactions. The detection of the biofilm was done using the tube adherence method. Drug susceptibility testing was done using the Kirby-Bauer disc diffusion method. Biofilm was detected in 73.4% isolates, whereas 26.6% of isolates were nonbiofilm producers. Mean duration of catheterization after which biofilm was detected was 5.01 ± 1.31 days. A latex catheter was used in 69.5% of patients, whereas a silicone catheter was used in 30.4% of patients. Escherichia coli was found to be the most common pathogen isolated (52.3%), whereas Enterobacter cloacae exhibited the highest biofilm production (87.5%) among isolated pathogens. Among biofilm producers, the highest resistance was observed with ampicillin (100%). Fosfomycin exhibited the lowest resistance (17.2%). Significant association with biofilm was detected for gender, duration of catheterization, and type of catheter. Biofilm-based CAUTI is an emerging problem. E coli was the most frequent isolate. High antibiotic resistance was observed in biofilm-producing strains. Using the variables affecting biofilm formation, tailored intervention strategies can be implemented to reduce biofilm-based CAUTIs. Copyright © 2017 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

  3. Pathogenic Leptospira species express surface-exposed proteins belonging to the bacterial immunoglobulin superfamily

    PubMed Central

    Matsunaga, James; Barocchi, Michele A.; Croda, Julio; Young, Tracy A.; Sanchez, Yolanda; Siqueira, Isadora; Bolin, Carole A.; Reis, Mitermayer G.; Riley, Lee W.; Haake, David A.; Ko, Albert I.

    2005-01-01

    Summary Proteins with bacterial immunoglobulin-like (Big) domains, such as the Yersinia pseudotuberculosis invasin and Escherichia coli intimin, are surface-expressed proteins that mediate host mammalian cell invasion or attachment. Here, we report the identification and characterization of a new family of Big domain proteins, referred to as Lig (leptospiral Ig-like) proteins, in pathogenic Leptospira. Screening of L. interrogans and L. kirschneri expression libraries with sera from leptospirosis patients identified 13 lambda phage clones that encode tandem repeats of the 90 amino acid Big domain. Two lig genes, designated ligA and ligB, and one pseudo-gene, ligC, were identified. The ligA and ligB genes encode amino-terminal lipoprotein signal peptides followed by 10 or 11 Big domain repeats and, in the case of ligB, a unique carboxy-terminal non-repeat domain. The organization of ligC is similar to that of ligB but contains mutations that disrupt the reading frame. The lig sequences are present in pathogenic but not saprophytic Leptospira species. LigA and LigB are expressed by a variety of virulent leptospiral strains. Loss of Lig protein and RNA transcript expression is correlated with the observed loss of virulence during culture attenuation of pathogenic strains. High-pressure freeze substitution followed by immunocytochemical electron microscopy confirmed that the Lig proteins were localized to the bacterial surface. Immunoblot studies with patient sera found that the Lig proteins are a major antigen recognized during the acute host infection. These observations demonstrate that the Lig proteins are a newly identified surface protein of pathogenic Leptospira, which by analogy to other bacterial immunoglobulin superfamily virulence factors, may play a role in host cell attachment and invasion during leptospiral pathogenesis. PMID:12890019

  4. A historical overview of bacteriophage therapy as an alternative to antibiotics for the treatment of bacterial pathogens.

    PubMed

    Wittebole, Xavier; De Roock, Sophie; Opal, Steven M

    2014-01-01

    The seemingly inexorable spread of antibiotic resistance genes among microbial pathogens now threatens the long-term viability of our current antimicrobial therapy to treat severe bacterial infections such as sepsis. Antibiotic resistance is reaching a crisis situation in some bacterial pathogens where few therapeutic alternatives remain and pan-resistant strains are becoming more prevalent. Non-antibiotic therapies to treat bacterial infections are now under serious consideration and one possible option is the therapeutic use of specific phage particles that target bacterial pathogens. Bacteriophage therapy has essentially been re-discovered by modern medicine after widespread use of phage therapy in the pre-antibiotic era lost favor, at least in Western countries, after the introduction of antibiotics. We review the current therapeutic rationale and clinical experience with phage therapy as a treatment for invasive bacterial infection as novel alternative to antimicrobial chemotherapy.

  5. A historical overview of bacteriophage therapy as an alternative to antibiotics for the treatment of bacterial pathogens

    PubMed Central

    Wittebole, Xavier; De Roock, Sophie; Opal, Steven M

    2014-01-01

    The seemingly inexorable spread of antibiotic resistance genes among microbial pathogens now threatens the long-term viability of our current antimicrobial therapy to treat severe bacterial infections such as sepsis. Antibiotic resistance is reaching a crisis situation in some bacterial pathogens where few therapeutic alternatives remain and pan-resistant strains are becoming more prevalent. Non-antibiotic therapies to treat bacterial infections are now under serious consideration and one possible option is the therapeutic use of specific phage particles that target bacterial pathogens. Bacteriophage therapy has essentially been re-discovered by modern medicine after widespread use of phage therapy in the pre-antibiotic era lost favor, at least in Western countries, after the introduction of antibiotics. We review the current therapeutic rationale and clinical experience with phage therapy as a treatment for invasive bacterial infection as novel alternative to antimicrobial chemotherapy. PMID:23973944

  6. Gram Stains: A Resource for Retrospective Analysis of Bacterial Pathogens in Clinical Studies

    PubMed Central

    Srinivasan, Usha; Ponnaluri, Sreelatha; Villareal, Lisa; Gillespie, Brenda; Wen, Ai; Miles, Arianna; Bucholz, Brigette; Marrs, Carl F.; Iyer, Ram K.; Misra, Dawn; Foxman, Betsy

    2012-01-01

    We demonstrate the feasibility of using qPCR on DNA extracted from vaginal Gram stain slides to estimate the presence and relative abundance of specific bacterial pathogens. We first tested Gram stained slides spiked with a mix of 108 cfu/ml of Escherichia coli and 105 cfu/ml of Lactobacillus acidophilus. Primers were designed for amplification of total and species-specific bacterial DNA based on 16S ribosomal gene regions. Sample DNA was pre-amplified with nearly full length 16S rDNA ribosomal gene fragment, followed by quantitative PCR with genera and species-specific 16S rDNA primers. Pre-amplification PCR increased the bacterial amounts; relative proportions of Escherichia coli and Lactobacillus recovered from spiked slides remained unchanged. We applied this method to forty two archived Gram stained slides available from a clinical trial of cerclage in pregnant women at high risk of preterm birth. We found a high correlation between Nugent scores based on bacterial morphology of Lactobacillus, Gardenerella and Mobiluncus and amounts of quantitative PCR estimated genus specific DNA (rrn copies) from Gram stained slides. Testing of a convenience sample of eight paired vaginal swabs and Gram stains freshly collected from healthy women found similar qPCR generated estimates of Lactobacillus proportions from Gram stained slides and vaginal swabs. Archived Gram stained slides collected from large scale epidemiologic and clinical studies represent a valuable, untapped resource for research on the composition of bacterial communities that colonize human mucosal surfaces. PMID:23071487

  7. Interaction between extracellular matrix molecules and microbial pathogens: evidence for the missing link in autoimmunity with rheumatoid arthritis as a disease model

    PubMed Central

    Sofat, Nidhi; Wait, Robin; Robertson, Saralili D.; Baines, Deborah L.; Baker, Emma H.

    2015-01-01

    Rheumatoid arthritis (RA) is an autoimmune disease characterized by inflammation followed by tissue rebuilding or fibrosis. A failure by the body to regulate inflammation effectively is one of the hallmarks of RA. The interaction between the external environment and the human host plays an important role in the development of autoimmunity. In RA, the observation of anti-cyclic citrullinated peptide antibodies (ACPA) to autoantigens is well recognized. Citrullination is a post-translational modification mediated by peptidyl arginine deiminases, which exist in both mammalian and bacterial forms. Previous studies have shown how proteins expressed in the human extracellular matrix (ECM) acquire properties of damage-associated molecular patterns (DAMPs) in RA and include collagens, tenascin-C, and fibronectin (FN). ECM DAMPs can further potentiate tissue damage in RA. Recent work has shown that citrullination in RA occurs at mucosal sites, including the oral cavity and lung. Mucosal sites have been linked with bacterial infection, e.g., periodontal disease, where exogenous pathogens are implicated in the development of autoimmunity via an infectious trigger. Proteases produced at mucosal sites, both by bacteria and the human host, can induce the release of ECM DAMPs, thereby revealing neoepitopes which can be citrullinated and lead to an autoantibody response with further production of ACPA. In this perspectives article, the evidence for the interplay between the ECM and bacteria at human mucosal surfaces, which can become a focus for citrullination and the development of autoimmunity, is explored. Specific examples, with reference to collagen, fibrinogen, and FN, are discussed. PMID:25642219

  8. Abundance and co-occurrence of extracellular capsules increase environmental breadth: Implications for the emergence of pathogens

    PubMed Central

    Néron, Bertrand; Touchon, Marie; Rocha, Eduardo P. C.

    2017-01-01

    Extracellular capsules constitute the outermost layer of many bacteria, are major virulence factors, and affect antimicrobial therapies. They have been used as epidemiological markers and recently became vaccination targets. Despite the efforts to biochemically serotype capsules in a few model pathogens, little is known of their taxonomic and environmental distribution. We developed, validated, and made available a computational tool, CapsuleFinder, to identify capsules in genomes. The analysis of over 2500 prokaryotic genomes, accessible in a database, revealed that ca. 50% of them—including Archaea—encode a capsule. The Wzx/Wzy-dependent capsular group was by far the most abundant. Surprisingly, a fifth of the genomes encode more than one capsule system—often from different groups—and their non-random co-occurrence suggests the existence of negative and positive epistatic interactions. To understand the role of multiple capsules, we queried more than 6700 metagenomes for the presence of species encoding capsules and showed that their distribution varied between environmental categories and, within the human microbiome, between body locations. Species encoding capsules, and especially those encoding multiple capsules, had larger environmental breadths than the other species. Accordingly, capsules were more frequent in environmental bacteria than in pathogens and, within the latter, they were more frequent among facultative pathogens. Nevertheless, capsules were frequent in clinical samples, and were usually associated with fast-growing bacteria with high infectious doses. Our results suggest that capsules increase the environmental range of bacteria and make them more resilient to environmental perturbations. Capsules might allow opportunistic pathogens to profit from empty ecological niches or environmental perturbations, such as those resulting from antibiotic therapy, to colonize the host. Capsule-associated virulence might thus be a by-product of

  9. Isolation and Identification of an Extracellular Subtilisin-Like Serine Protease Secreted by the Bat Pathogen Pseudogymnoascus destructans

    PubMed Central

    Pannkuk, Evan L.; Risch, Thomas S.; Savary, Brett J.

    2015-01-01

    White nose syndrome (WNS) is a cutaneous fungal disease of bats. WNS is responsible for unprecedented mortalities in North American cave bat populations. There have been few descriptions of enzyme activities that may function in WNS host/pathogen interactions, while no study has isolated and described secreted proteases. To address the hypothesis that Pseudogymnoascus destructans secretes extracellular proteases that function in wing necrosis during WNS infection, the object of this study was to culture P. destructans on various media, then isolate and structurally identify those proteases accumulated stably in the culture medium. We found a single dominant protease activity on minimal nutrient broth enriched with protein substrates, which was strongly inhibited by phenylmethylsulfonyl fluoride. This P. destructans serine protease (PdSP1) was isolated by preparative isoelectric focusing and concanavalin A lectin affinity chromatography. PdSP1 showed a molecular weight 27,900 (estimated by SDS-PAGE), broad pH optimum 6-8, and temperature optimum 60°C. Structural characterization of PdSP1 by MALDI-TOF MS, Orbitrap MS/MS, and Edman amino-terminal peptide sequencing matched it directly to a hypothetical protein accession from the sequenced P. destructans genome that is further identified as a MEROPS family S8A subtilisin-like serine peptidase. Two additional isoforms, PdSP2 and PdSP3, were identified in the P. destructans genome with 90% and 53% homology, respectively. P. destructans S8A serine proteases showed closer sequence conservation to P. pannorum and plant pathogenic fungi than to human pathogenic dermatophytes. Peptide-specific polyclonal antibodies developed from the PdSP1 sequence detected the protein in western blots. These subtilisin-like serine proteases are candidates for further functional studies in WNS host-pathogen interaction. PMID:25785714

  10. Isolation and identification of an extracellular subtilisin-like serine protease secreted by the bat pathogen Pseudogymnoascus destructans.

    PubMed

    Pannkuk, Evan L; Risch, Thomas S; Savary, Brett J

    2015-01-01

    White nose syndrome (WNS) is a cutaneous fungal disease of bats. WNS is responsible for unprecedented mortalities in North American cave bat populations. There have been few descriptions of enzyme activities that may function in WNS host/pathogen interactions, while no study has isolated and described secreted proteases. To address the hypothesis that Pseudogymnoascus destructans secretes extracellular proteases that function in wing necrosis during WNS infection, the object of this study was to culture P. destructans on various media, then isolate and structurally identify those proteases accumulated stably in the culture medium. We found a single dominant protease activity on minimal nutrient broth enriched with protein substrates, which was strongly inhibited by phenylmethylsulfonyl fluoride. This P. destructans serine protease (PdSP1) was isolated by preparative isoelectric focusing and concanavalin A lectin affinity chromatography. PdSP1 showed a molecular weight 27,900 (estimated by SDS-PAGE), broad pH optimum 6-8, and temperature optimum 60°C. Structural characterization of PdSP1 by MALDI-TOF MS, Orbitrap MS/MS, and Edman amino-terminal peptide sequencing matched it directly to a hypothetical protein accession from the sequenced P. destructans genome that is further identified as a MEROPS family S8A subtilisin-like serine peptidase. Two additional isoforms, PdSP2 and PdSP3, were identified in the P. destructans genome with 90% and 53% homology, respectively. P. destructans S8A serine proteases showed closer sequence conservation to P. pannorum and plant pathogenic fungi than to human pathogenic dermatophytes. Peptide-specific polyclonal antibodies developed from the PdSP1 sequence detected the protein in western blots. These subtilisin-like serine proteases are candidates for further functional studies in WNS host-pathogen interaction.

  11. Multidirectional chemical signalling between Mammalian hosts, resident microbiota, and invasive pathogens: neuroendocrine hormone-induced changes in bacterial gene expression.

    PubMed

    Karavolos, Michail H; Khan, C M Anjam

    2014-01-01

    Host-pathogen communication appears to be crucial in establishing the outcome of bacterial infections. There is increasing evidence to suggest that this communication can take place by bacterial pathogens sensing and subsequently responding to host neuroendocrine (NE) stress hormones. Bacterial pathogens have developed mechanisms allowing them to eavesdrop on these communication pathways within their hosts. These pathogens can use intercepted communication signals to adjust their fitness to persist and cause disease in their hosts. Recently, there have been numerous studies highlighting the ability of NE hormones to act as an environmental cue for pathogens, helping to steer their responses during host infection. Host NE hormone sensing can take place indirectly or directly via bacterial adrenergic receptors (BARs). The resulting changes in bacterial gene expression can be of strategic benefit to the pathogen. Furthermore, it is intriguing that not only can bacteria sense NE stress hormones but they are also able to produce key signalling molecules known as autoinducers. The rapid advances in our knowledge of the human microbiome, and its impact on health and disease highlights the potential importance of communication between the microbiota, pathogens and the host. It is indeed likely that the microbiota input significantly in the neuroendocrinological homeostasis of the host by catabolic, anabolic, and signalling processes. The arrival of unwanted guests, such as bacterial pathogens, clearly has a major impact on these delicately balanced interactions. Unravelling the pathways involved in interkingdom communication between invading bacterial pathogens, the resident microbiota, and hosts, may provide novel targets in our continuous search for new antimicrobials to control disease.

  12. Simultaneous Detection of Nine Key Bacterial Respiratory Pathogens Using Luminex xTAG® Technology

    PubMed Central

    Jiang, Luxi; Ren, Hongyu; Zhou, Haijian; Qin, Tian; Chen, Yu

    2017-01-01

    Early diagnosis and treatment are crucial to the outcome of lower respiratory tract infections (LRTIs). In this study, we developed an assay combining multiplex PCR and Luminex technology (MPLT) for the detection of nine important respiratory bacterial pathogens, which frequently cause LRTIs. These were Streptococcus pneumoniae, Moraxella catarrhalis, Staphylococcus aureus, Streptococcus pyogenes, Haemophilus influenzae, Mycoplasma pneumoniae, Legionella spp., Pseudomonas aeruginosa, and Klebsiella pneumoniae. Through the hybridization reaction between two new synthesized multiplex PCR products and MagPlex-TAG Microspheres, we demonstrate that the detection limits for these nine pathogens were as low as 102–103 CFU/mL. Furthermore, 86 clinical bronchoalveolar lavage fluid specimens were used to evaluate this method. Compared with the results of nine simplex real-time PCR reactions targeting these nine pathogens, this MPLT assay demonstrated a high diagnostic accuracy for Streptococcus pneumoniae (sensitivity, 87.5% and specificity, 100%). Furthermore, sensitivity and specificity for the other eight pathogens all attained 100% diagnostic accuracy. In addition, the consistency between MPLT and the nine real-time PCR reactions exceeded 98.8%. In conclusion, MPLT is a high-throughput, labor-saving and reliable method with high sensitivity and specificity for identifying nine respiratory pathogens responsible for LRTIs. Indeed, this assay may be a promising supplement to conventional methods used to diagnose LRTIs. PMID:28241513

  13. Rapid methods for the detection of foodborne bacterial pathogens: principles, applications, advantages and limitations

    PubMed Central

    Law, Jodi Woan-Fei; Ab Mutalib, Nurul-Syakima; Chan, Kok-Gan; Lee, Learn-Han

    2015-01-01

    The incidence of foodborne diseases has increased over the years and resulted in major public health problem globally. Foodborne pathogens can be found in various foods and it is important to detect foodborne pathogens to provide safe food supply and to prevent foodborne diseases. The conventional methods used to detect foodborne pathogen are time consuming and laborious. Hence, a variety of methods have been developed for rapid detection of foodborne pathogens as it is required in many food analyses. Rapid detection methods can be categorized into nucleic acid-based, biosensor-based and immunological-based methods. This review emphasizes on the principles and application of recent rapid methods for the detection of foodborne bacterial pathogens. Detection methods included are simple polymerase chain reaction (PCR), multiplex PCR, real-time PCR, nucleic acid sequence-based amplification (NASBA), loop-mediated isothermal amplification (LAMP) and oligonucleotide DNA microarray which classified as nucleic acid-based methods; optical, electrochemical and mass-based biosensors which classified as biosensor-based methods; enzyme-linked immunosorbent assay (ELISA) and lateral flow immunoassay which classified as immunological-based methods. In general, rapid detection methods are generally time-efficient, sensitive, specific and labor-saving. The developments of rapid detection methods are vital in prevention and treatment of foodborne diseases. PMID:25628612

  14. Rapid methods for the detection of foodborne bacterial pathogens: principles, applications, advantages and limitations.

    PubMed

    Law, Jodi Woan-Fei; Ab Mutalib, Nurul-Syakima; Chan, Kok-Gan; Lee, Learn-Han

    2014-01-01

    The incidence of foodborne diseases has increased over the years and resulted in major public health problem globally. Foodborne pathogens can be found in various foods and it is important to detect foodborne pathogens to provide safe food supply and to prevent foodborne diseases. The conventional methods used to detect foodborne pathogen are time consuming and laborious. Hence, a variety of methods have been developed for rapid detection of foodborne pathogens as it is required in many food analyses. Rapid detection methods can be categorized into nucleic acid-based, biosensor-based and immunological-based methods. This review emphasizes on the principles and application of recent rapid methods for the detection of foodborne bacterial pathogens. Detection methods included are simple polymerase chain reaction (PCR), multiplex PCR, real-time PCR, nucleic acid sequence-based amplification (NASBA), loop-mediated isothermal amplification (LAMP) and oligonucleotide DNA microarray which classified as nucleic acid-based methods; optical, electrochemical and mass-based biosensors which classified as biosensor-based methods; enzyme-linked immunosorbent assay (ELISA) and lateral flow immunoassay which classified as immunological-based methods. In general, rapid detection methods are generally time-efficient, sensitive, specific and labor-saving. The developments of rapid detection methods are vital in prevention and treatment of foodborne diseases.

  15. Structure of the extracellular portion of CD46 provides insights into its interactions with complement proteins and pathogens.

    PubMed

    Persson, B David; Schmitz, Nikolaus B; Santiago, César; Zocher, Georg; Larvie, Mykol; Scheu, Ulrike; Casasnovas, José M; Stehle, Thilo

    2010-09-30

    The human membrane cofactor protein (MCP, CD46) is a central component of the innate immune system. CD46 protects autologous cells from complement attack by binding to complement proteins C3b and C4b and serving as a cofactor for their cleavage. Recent data show that CD46 also plays a role in mediating acquired immune responses, and in triggering autophagy. In addition to these physiologic functions, a significant number of pathogens, including select adenoviruses, measles virus, human herpes virus 6 (HHV-6), Streptococci, and Neisseria, use CD46 as a cell attachment receptor. We have determined the crystal structure of the extracellular region of CD46 in complex with the human adenovirus type 11 fiber knob. Extracellular CD46 comprises four short consensus repeats (SCR1-SCR4) that form an elongated structure resembling a hockey stick, with a long shaft and a short blade. Domains SCR1, SCR2 and SCR3 are arranged in a nearly linear fashion. Unexpectedly, however, the structure reveals a profound bend between domains SCR3 and SCR4, which has implications for the interactions with ligands as well as the orientation of the protein at the cell surface. This bend can be attributed to an insertion of five hydrophobic residues in a SCR3 surface loop. Residues in this loop have been implicated in interactions with complement, indicating that the bend participates in binding to C3b and C4b. The structure provides an accurate framework for mapping all known ligand binding sites onto the surface of CD46, thereby advancing an understanding of how CD46 acts as a receptor for pathogens and physiologic ligands of the immune system.

  16. Contribution of AmyA, an extracellular α-glucan degrading enzyme, to group A streptococcal host-pathogen interaction

    PubMed Central

    Shelburne, Samuel A.; Keith, David B.; Davenport, Michael T.; Beres, Stephen B.; Carroll, Ronan K.; Musser, James M.

    2010-01-01

    α-glucans such as starch and glycogen are abundant in the human oropharynx, the main site of group A Streptococcus (GAS) infection. However, the role in pathogenesis of GAS extracellular α-glucan binding and degrading enzymes is unknown. The serotype M1 GAS genome encodes two extracellular proteins putatively involved in α-glucan binding and degradation; pulA encodes a cell-wall anchored pullulanase and amyA encodes a freely secreted putative cyclomaltodextrin α-glucanotransferase. Genetic inactivation of amyA, but not pulA, abolished GAS α-glucan degradation. The ΔamyA strain had a slower rate of translocation across human pharyngeal epithelial cells. Consistent with this finding, the ΔamyA strain was less virulent following mouse mucosal challenge. Recombinant AmyA degraded α-glucans into β-cyclomaltodextrins that reduced pharyngeal cell transepithelial resistance, providing a physiologic explanation for the observed transepithelial migration phenotype. Higher amyA transcript levels were present in serotype M1 GAS strains causing invasive infection compared to strains causing pharyngitis. GAS proliferation in a defined α-glucan-containing medium was dependent on the presence of human salivary α-amylase. These data delineate the molecular mechanisms by which α-glucan degradation contributes to GAS host-pathogen interaction including how GAS employs human salivary α-amylase for its own metabolic benefit. PMID:19735442

  17. Extrinsic extracellular DNA leads to biofilm formation and colocalizes with matrix polysaccharides in the human pathogenic fungus Aspergillus fumigatus

    PubMed Central

    Shopova, Iordana; Bruns, Sandra; Thywissen, Andreas; Kniemeyer, Olaf; Brakhage, Axel A.; Hillmann, Falk

    2013-01-01

    The environmentally acquired fungal pathogen Aspergillus fumigatus causes a variety of severe diseases. Furthermore, it is often found colonizing the respiratory tract of patients suffering from cystic fibrosis. Conidia of this filamentous fungus adhere to substrate surfaces and germinate to form biofilms comprised of dense hyphal networks embedded in an adhesive extracellular matrix (ECM), built predominantly of polysaccharides. These fungal microconsortia are likely to be of clinical relevance, as they have also been observed during growth in the host and they confer drastically reduced susceptibility to antifungals. Little is known about environmental factors or signals contributing to the formation and structural organization of this polysaccharide matrix. Extracellular DNA (eDNA) is an abundant molecule in the mucus-rich surfaces in the lungs of cystic fibrosis patients. Here, we studied its influence on the biofilm establishment and progression of A. fumigatus. Using an in vitro biofilm model eDNA was identified as an efficient biofilm inducer promoting conidial surface adhesion and polysaccharide ECM production. Confocal laser scanning microscopy revealed entirely different ECM architectures depending on the substrates used for biofilm induction. In the presence of serum, adhesive polysaccharides were mainly localized to the hyphal tips appearing as cohesive threads or “halo” areas agglutinating the hyphae. Exogenous DNA altered the structural organization of the biofilm specifically by colocalizing to a grid-like bottom layer of ECM. These results indicate that biofilm formation in A. fumigatus is shaped by certain substrates and in response to host environmental signals. PMID:23760756

  18. Liquid based formulations of bacteriophages for the management of waterborne bacterial pathogens in water microcosms.

    PubMed

    Ahiwale, Sangeeta; Tagunde, Sujata; Khopkar, Sushama; Karni, Mrudula; Gajbhiye, Milind; Kapadnis, Balasaheb

    2013-11-01

    Water resources are contaminated by life-threatening multidrug resistant pathogenic bacteria. Unfortunately, these pathogenic bacteria do not respond to the traditional water purification methods. Therefore, there is a need of environmentally friendly strategies to overcome the problems associated with the antimicrobial resistant bacterial pathogens. In the present study, highly potent lytic phages against multidrug-resistant Salmonella enterica serovar Paratyphi B, Pseudomonas aeruginosa and Klebsiella pneumoniae were isolated from the Pavana river water. They belonged to the Podoviridae and Siphoviridae families. These phages were purified and enriched in the laboratory. Monovalent formulations of phiSPB, BVPaP-3 and KPP phages were prepared in three different liquids viz., phage broth, saline and distilled water. The phages were stable for almost 8-10 months in the phage broth at 4 degrees C. The stability of the phages in saline and distilled water was 5-6 months at 4 degrees C. All of the phages were stable only for 4-6 months in the phage broth at 30 degrees C. The monovalent phage formulation of psiSPB was applied at MOI < 1, as disinfectant against an exponential and stationary phase cells of Salmonella enterica serovar Paratyphi B in various water microcosms. The results indicated that there was almost 80 % reduction in the log phase cells of Salmonella serovar Paratyphi B in 24 h. In stationary phase cells, the reduction was comparatively less within same period. At the same time, there was concomitant increase in the phage population by 80% in all the microcosms indicating that psiSPB phage is highly potent in killing pathogen in water. Results strongly support that the formulation of psiSPB in the phage broth in monovalent form could be used as an effective biological disinfectant for preventing transmission of water-borne bacterial pathogens, including antimicrobial resistant ones.

  19. Occurrence and Persistence of Bacterial Pathogens and Indicator Organisms in Beach Sand along the California Coast

    PubMed Central

    Yamahara, Kevan M.; Sassoubre, Lauren M.; Goodwin, Kelly D.

    2012-01-01

    This report documents the presence of fecal indicators and bacterial pathogens in sand at 53 California marine beaches using both culture-dependent and -independent (PCR and quantitative PCR [QPCR]) methods. Fecal indicator bacteria were widespread in California beach sand, with Escherichia coli and enterococci detected at 68% and 94% of the beaches surveyed, respectively. Somatic coliphages and a Bacteroidales human-specific fecal marker were detected at 43% and 13% of the beaches, respectively. Dry sand samples from almost 30% of the beaches contained at least one of the following pathogens: Salmonella spp., Campylobacter spp., Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus (MRSA), which were detected at 15%, 13%, 14%, and 3% of tested beaches, respectively. Fecal indicators and pathogens were poorly correlated to one another and to land cover. Sands were dry at the time of collection, and those with relatively high moisture tended to have higher concentrations or a more frequent occurrence of both indicators and pathogens. Using culture-dependent assays, fecal indicators decayed faster than pathogens in microcosm experiments using unaltered beach sand seeded with sewage and assessed by culture-dependent assays. The following order of persistence was observed (listed from most to least persistent): Campylobacter > Salmonella > somatic coliphages > enterococci > E. coli > F+ phages. In contrast, pathogens decayed faster than fecal indicators in culture-independent assays: enterococci > Bacteroidales human-specific marker > Salmonella > Campylobacter. Microcosm experiments demonstrated that both indicators and pathogens were mobilized by wetting with seawater. Decay rates measured by QPCR were lower than those measured with culture-dependent methods. Enterococcal persistence and possible growth were observed for wetted microcosms relative to unwetted controls. PMID:22247142

  20. Occurrence and persistence of bacterial pathogens and indicator organisms in beach sand along the California coast.

    PubMed

    Yamahara, Kevan M; Sassoubre, Lauren M; Goodwin, Kelly D; Boehm, Alexandria B

    2012-03-01

    This report documents the presence of fecal indicators and bacterial pathogens in sand at 53 California marine beaches using both culture-dependent and -independent (PCR and quantitative PCR [QPCR]) methods. Fecal indicator bacteria were widespread in California beach sand, with Escherichia coli and enterococci detected at 68% and 94% of the beaches surveyed, respectively. Somatic coliphages and a Bacteroidales human-specific fecal marker were detected at 43% and 13% of the beaches, respectively. Dry sand samples from almost 30% of the beaches contained at least one of the following pathogens: Salmonella spp., Campylobacter spp., Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus (MRSA), which were detected at 15%, 13%, 14%, and 3% of tested beaches, respectively. Fecal indicators and pathogens were poorly correlated to one another and to land cover. Sands were dry at the time of collection, and those with relatively high moisture tended to have higher concentrations or a more frequent occurrence of both indicators and pathogens. Using culture-dependent assays, fecal indicators decayed faster than pathogens in microcosm experiments using unaltered beach sand seeded with sewage and assessed by culture-dependent assays. The following order of persistence was observed (listed from most to least persistent): Campylobacter > Salmonella > somatic coliphages > enterococci > E. coli > F(+) phages. In contrast, pathogens decayed faster than fecal indicators in culture-independent assays: enterococci > Bacteroidales human-specific marker > Salmonella > Campylobacter. Microcosm experiments demonstrated that both indicators and pathogens were mobilized by wetting with seawater. Decay rates measured by QPCR were lower than those measured with culture-dependent methods. Enterococcal persistence and possible growth were observed for wetted microcosms relative to unwetted controls.

  1. Composition and extracellular enzymatic function of pelagic, particle-associated, and benthic bacterial communities in the central Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Balmonte, J. P.; Teske, A.; Arnosti, C.

    2016-02-01

    The structure and function of Arctic bacterial communities have rarely been studied in concert, but are crucial to our understanding of biogeochemical cycles. As the Arctic transitions to become seasonally-ice free, a critical priority is to elucidate the present ecological role and environmental dependence of Arctic bacterial communities. We investigated the depth and regional variations in Central Arctic bacterial community composition (BCC) and extracellular enzymatic activities (EEA)—the initial step in organic matter breakdown—to explore links between community structure and function. Samples were collected across a gradient of sea-ice cover (open ocean, first year ice, multi-year ice) from 79°N to 88°N and from surface to bottom waters ( 3.5 to 4.5 km). Pelagic BCC most strongly varies with hydrography and with particle-association, which likely selects for a specialized community of heterotrophic opportunists; benthic BCC show little regional variation. In contrast, EEA reveal significant depth and regional differences in hydrolysis rates as well as in the spectrum of substrates hydrolyzed. Particle-associated EEA reveal an equal or greater range of enzymatic capabilities than in bulk-seawater measurements, supporting previous findings that particles are hotspots of microbial heterotrophic activity. These patterns suggest a complex relationship between BCC, EEA, and the environment: while water mass characteristics consistently differentiate bacterial communities, additional local factors shape their capabilities to hydrolyze organic matter. Multivariate analyses will be used to further explore the relationships between composition and function as well as their correlations with environmental data. Our findings provide a baseline for future comparisons and initial insight into the functionality and biogeography of Arctic bacterial communities.

  2. Nitrate, nitrite and nitric oxide reductases: from the last universal common ancestor to modern bacterial pathogens.

    PubMed

    Vázquez-Torres, Andrés; Bäumler, Andreas J

    2016-02-01

    The electrochemical gradient that ensues from the enzymatic activity of cytochromes such as nitrate reductase, nitric oxide reductase, and quinol oxidase contributes to the bioenergetics of the bacterial cell. Reduction of nitrogen oxides by bacterial pathogens can, however, be uncoupled from proton translocation and biosynthesis of ATP or NH4(+), but still linked to quinol and NADH oxidation. Ancestral nitric oxide reductases, as well as cytochrome c oxidases and quinol bo oxidases evolved from the former, are capable of binding and detoxifying nitric oxide to nitrous oxide. The NO-metabolizing activity associated with these cytochromes can be a sizable source of antinitrosative defense in bacteria during their associations with host cells. Nitrosylation of terminal cytochromes arrests respiration, reprograms bacterial metabolism, stimulates antioxidant defenses and alters antibiotic cytotoxicity. Collectively, the bioenergetics and regulation of redox homeostasis that accompanies the utilization of nitrogen oxides and detoxification of nitric oxide by cytochromes of the electron transport chain increases fitness of many Gram-positive and -negative pathogens during their associations with invertebrate and vertebrate hosts.

  3. Titanium dioxide nanoparticles enhance mortality of fish exposed to bacterial pathogens.

    PubMed

    Jovanović, Boris; Whitley, Elizabeth M; Kimura, Kayoko; Crumpton, Adam; Palić, Dušan

    2015-08-01

    Nano-TiO2 is immunotoxic to fish and reduces the bactericidal function of fish neutrophils. Here, fathead minnows (Pimephales promelas) were exposed to low and high environmentally relevant concentration of nano-TiO2 (2 ng g(-1) and 10 μg g(-1) body weight, respectively), and were challenged with common fish bacterial pathogens, Aeromonas hydrophila or Edwardsiella ictaluri. Pre-exposure to nano-TiO2 significantly increased fish mortality during bacterial challenge. Nano-TiO2 concentrated in the kidney and spleen. Phagocytosis assay demonstrated that nano-TiO2 has the ability to diminish neutrophil phagocytosis of A. hydrophila. Fish injected with TiO2 nanoparticles displayed significant histopathology when compared to control fish. The interplay between nanoparticle exposure, immune system, histopathology, and infectious disease pathogenesis in any animal model has not been described before. By modulating fish immune responses and interfering with resistance to bacterial pathogens, manufactured nano-TiO2 has the potential to affect fish survival in a disease outbreak.

  4. Inhibitory Effect of Camptothecin against Rice Bacterial Brown Stripe Pathogen Acidovorax avenae subsp. avenae RS-2.

    PubMed

    Dong, Qiaolin; Luo, Ju; Qiu, Wen; Cai, Li; Anjum, Syed Ishtiaq; Li, Bin; Hou, Mingsheng; Xie, Guanlin; Sun, Guochang

    2016-07-27

    Camptothecin (CPT) has anticancer, antiviral, and antifungal properties. However, there is a dearth of information about antibacterial activity of CPT. Therefore, in this study, we investigated the inhibitory effect of CPT on Acidovorax avenae subsp. avenae strain RS-2, the pathogen of rice bacterial brown stripe, by measuring cell growth, DNA damage, cell membrane integrity, the expression of secretion systems, and topoisomerase-related genes, as well as the secretion of effector protein Hcp. Results indicated that CPT solutions at 0.05, 0.25, and 0.50 mg/mL inhibited the growth of strain RS-2 in vitro, while the inhibitory efficiency increased with an increase in CPT concentration, pH, and incubation time. Furthermore, CPT treatment affected bacterial growth and replication by causing membrane damage, which was evidenced by transmission electron microscopic observation and live/dead cell staining. In addition, quantitative real-time PCR analysis indicated that CPT treatment caused differential expression of eight secretion system-related genes and one topoisomerase-related gene, while the up-regulated expression of hcp could be justified by the increased secretion of Hcp based on the ELISA test. Overall, this study indicated that CPT has the potential to control the bacterial brown stripe pathogen of rice.

  5. Nitrate, nitrite and nitric oxide reductases: from the last universal common ancestor to modern bacterial pathogens

    PubMed Central

    Vázquez-Torres, Andrés; Bäumler, Andreas

    2016-01-01

    The electrochemical gradient that ensues from the enzymatic activity of cytochromes such as nitrate reductase, nitric oxide reductase, and quinol oxidase contributes to the bioenergetics of the bacterial cell. Reduction of nitrogen oxides by bacterial pathogens can, however, be uncoupled from proton translocation and biosynthesis of ATP or NH4+, but still linked to quinol and NADH oxidation. Ancestral nitric oxide reductases, as well as cytochrome coxidases and quinol bo oxidases evolved from the former, are capable of binding and detoxifying nitric oxide to nitrous oxide. The NO-metabolizing activity associated with these cytochromes can be a sizable source of antinitrosative defense in bacteria during their associations with host cells. Nitrosylation of terminal cytochromes arrests respiration, reprograms bacterial metabolism, stimulates antioxidant defenses and alters antibiotic cytotoxicity. Collectively, the bioenergetics and regulation of redox homeostasis that accompanies the utilization of nitrogen oxides and detoxification of nitric oxide by cytochromes of the electron transport chain increases fitness of many Gram-positive and –negative pathogens during their associations with invertebrate and vertebrate hosts. PMID:26426528

  6. Phage-protease-peptide: a novel trifecta enabling multiplex detection of viable bacterial pathogens.

    PubMed

    Alcaine, S D; Tilton, L; Serrano, M A C; Wang, M; Vachet, R W; Nugen, S R

    2015-10-01

    Bacteriophages represent rapid, readily targeted, and easily produced molecular probes for the detection of bacterial pathogens. Molecular biology techniques have allowed researchers to make significant advances in the bioengineering of bacteriophage to further improve speed and sensitivity of detection. Despite their host specificity, bacteriophages have not been meaningfully leveraged in multiplex detection of bacterial pathogens. We propose a proof-of-principal phage-based scheme to enable multiplex detection. Our scheme involves bioengineering bacteriophage to carry a gene for a specific protease, which is expressed during infection of the target cell. Upon lysis, the protease is released to cleave a reporter peptide, and the signal detected. Here we demonstrate the successful (i) modification of T7 bacteriophage to carry tobacco etch virus (TEV) protease; (ii) expression of TEV protease by Escherichia coli following infection by our modified T7, an average of 2000 units of protease per phage are produced during infection; and (iii) proof-of-principle detection of E. coli in 3 h after a primary enrichment via TEV protease activity using a fluorescent peptide and using a designed target peptide for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis (MALDI-TOF MS) analysis. This proof-of-principle can be translated to other phage-protease-peptide combinations to enable multiplex bacterial detection and readily adopted on multiple platforms, like MALDI-TOF MS or fluorescent readers, commonly found in labs.

  7. A Comparison between Transcriptome Sequencing and 16S Metagenomics for Detection of Bacterial Pathogens in Wildlife.

    PubMed

    Razzauti, Maria; Galan, Maxime; Bernard, Maria; Maman, Sarah; Klopp, Christophe; Charbonnel, Nathalie; Vayssier-Taussat, Muriel; Eloit, Marc; Cosson, Jean-François

    2015-01-01

    Rodents are major reservoirs of pathogens responsible for numerous zoonotic diseases in humans and livestock. Assessing their microbial diversity at both the individual and population level is crucial for monitoring endemic infections and revealing microbial association patterns within reservoirs. Recently, NGS approaches have been employed to characterize microbial communities of different ecosystems. Yet, their relative efficacy has not been assessed. Here, we compared two NGS approaches, RNA-Sequencing (RNA-Seq) and 16S-metagenomics, assessing their ability to survey neglected zoonotic bacteria in rodent populations. We first extracted nucleic acids from the spleens of 190 voles collected in France. RNA extracts were pooled, randomly retro-transcribed, then RNA-Seq was performed using HiSeq. Assembled bacterial sequences were assigned to the closest taxon registered in GenBank. DNA extracts were analyzed via a 16S-metagenomics approach using two sequencers: the 454 GS-FLX and the MiSeq. The V4 region of the gene coding for 16S rRNA was amplified for each sample using barcoded universal primers. Amplicons were multiplexed and processed on the distinct sequencers. The resulting datasets were de-multiplexed, and each read was processed through a pipeline to be taxonomically classified using the Ribosomal Database Project. Altogether, 45 pathogenic bacterial genera were detected. The bacteria identified by RNA-Seq were comparable to those detected by 16S-metagenomics approach processed with MiSeq (16S-MiSeq). In contrast, 21 of these pathogens went unnoticed when the 16S-metagenomics approach was processed via 454-pyrosequencing (16S-454). In addition, the 16S-metagenomics approaches revealed a high level of coinfection in bank voles. We concluded that RNA-Seq and 16S-MiSeq are equally sensitive in detecting bacteria. Although only the 16S-MiSeq method enabled identification of bacteria in each individual reservoir, with subsequent derivation of bacterial prevalence

  8. A Comparison between Transcriptome Sequencing and 16S Metagenomics for Detection of Bacterial Pathogens in Wildlife

    PubMed Central

    Razzauti, Maria; Galan, Maxime; Bernard, Maria; Maman, Sarah; Klopp, Christophe; Charbonnel, Nathalie; Vayssier-Taussat, Muriel; Eloit, Marc; Cosson, Jean-François

    2015-01-01

    Background Rodents are major reservoirs of pathogens responsible for numerous zoonotic diseases in humans and livestock. Assessing their microbial diversity at both the individual and population level is crucial for monitoring endemic infections and revealing microbial association patterns within reservoirs. Recently, NGS approaches have been employed to characterize microbial communities of different ecosystems. Yet, their relative efficacy has not been assessed. Here, we compared two NGS approaches, RNA-Sequencing (RNA-Seq) and 16S-metagenomics, assessing their ability to survey neglected zoonotic bacteria in rodent populations. Methodology/Principal Findings We first extracted nucleic acids from the spleens of 190 voles collected in France. RNA extracts were pooled, randomly retro-transcribed, then RNA-Seq was performed using HiSeq. Assembled bacterial sequences were assigned to the closest taxon registered in GenBank. DNA extracts were analyzed via a 16S-metagenomics approach using two sequencers: the 454 GS-FLX and the MiSeq. The V4 region of the gene coding for 16S rRNA was amplified for each sample using barcoded universal primers. Amplicons were multiplexed and processed on the distinct sequencers. The resulting datasets were de-multiplexed, and each read was processed through a pipeline to be taxonomically classified using the Ribosomal Database Project. Altogether, 45 pathogenic bacterial genera were detected. The bacteria identified by RNA-Seq were comparable to those detected by 16S-metagenomics approach processed with MiSeq (16S-MiSeq). In contrast, 21 of these pathogens went unnoticed when the 16S-metagenomics approach was processed via 454-pyrosequencing (16S-454). In addition, the 16S-metagenomics approaches revealed a high level of coinfection in bank voles. Conclusions/Significance We concluded that RNA-Seq and 16S-MiSeq are equally sensitive in detecting bacteria. Although only the 16S-MiSeq method enabled identification of bacteria in each

  9. An Overview of the Control of Bacterial Pathogens in Cattle Manure

    PubMed Central

    Manyi-Loh, Christy E.; Mamphweli, Sampson N.; Meyer, Edson L.; Makaka, Golden; Simon, Michael; Okoh, Anthony I.

    2016-01-01

    Cattle manure harbors microbial constituents that make it a potential source of pollution in the environment and infections in humans. Knowledge of, and microbial assessment of, manure is crucial in a bid to prevent public health and environmental hazards through the development of better management practices and policies that should govern manure handling. Physical, chemical and biological methods to reduce pathogen population in manure do exist, but are faced with challenges such as cost, odor pollution, green house gas emission, etc. Consequently, anaerobic digestion of animal manure is currently one of the most widely used treatment method that can help to salvage the above-mentioned adverse effects and in addition, produces biogas that can serve as an alternative/complementary source of energy. However, this method has to be monitored closely as it could be fraught with challenges during operation, caused by the inherent characteristics of the manure. In addition, to further reduce bacterial pathogens to a significant level, anaerobic digestion can be combined with other methods such as thermal, aerobic and physical methods. In this paper, we review the bacterial composition of cattle manure as well as methods engaged in the control of pathogenic microbes present in manure and recommendations that need to be respected and implemented in order to prevent microbial contamination of the environment, animals and humans. PMID:27571092

  10. Comparative and bioinformatics analyses of pathogenic bacterial secretomes identified by mass spectrometry in Burkholderia species.

    PubMed

    Nguyen, Thao Thi; Chon, Tae-Soo; Kim, Jaehan; Seo, Young-Su; Heo, Muyoung

    2017-07-01

    Secreted proteins (secretomes) play crucial roles during bacterial pathogenesis in both plant and human hosts. The identification and characterization of secretomes in the two plant pathogens Burkholderia glumae BGR1 and B. gladioli BSR3, which cause diseases in rice such as seedling blight, panicle blight, and grain rot, are important steps to not only understand the disease-causing mechanisms but also find remedies for the diseases. Here, we identified two datasets of secretomes in B. glumae BGR1 and B. gladioli BSR3, which consist of 118 and 111 proteins, respectively, using mass spectrometry approach and literature curation. Next, we characterized the functional properties, potential secretion pathways and sequence information properties of secretomes of two plant pathogens in a comparative analysis by various computational approaches. The ratio of potential non-classically secreted proteins (NCSPs) to classically secreted proteins (CSPs) in B. glumae BGR1 was greater than that in B. gladioli BSR3. For CSPs, the putative hydrophobic regions (PHRs) which are essential for secretion process of CSPs were screened in detail at their N-terminal sequences using hidden Markov model (HMM)-based method. Total 31 pairs of homologous proteins in two bacterial secretomes were indicated based on the global alignment (identity ≥ 70%). Our results may facilitate the understanding of the species-specific features of secretomes in two plant pathogenic Burkholderia species.

  11. Inactivation of Selected Bacterial Pathogens in Dairy Cattle Manure by Mesophilic Anaerobic Digestion (Balloon Type Digester)

    PubMed Central

    Manyi-Loh, Christy E.; Mamphweli, Sampson N.; Meyer, Edson L.; Okoh, Anthony I.; Makaka, Golden; Simon, Michael

    2014-01-01

    Anaerobic digestion of animal manure in biogas digesters has shown promise as a technology in reducing the microbial load to safe and recommended levels. We sought to treat dairy manure obtained from the Fort Hare Dairy Farm by investigating the survival rates of bacterial pathogens, through a total viable plate count method, before, during and after mesophilic anaerobic digestion. Different microbiological media were inoculated with different serial dilutions of manure samples that were withdrawn from the biogas digester at 3, 7 and 14 day intervals to determine the viable cells. Data obtained indicated that the pathogens of public health importance were 90%–99% reduced in the order: Campylobacter sp. (18 days) < Escherichia coli sp. (62 days) < Salmonella sp. (133 days) from a viable count of 10.1 × 103, 3.6 × 105, 7.4 × 103 to concentrations below the detection limit (DL = 102 cfu/g manure), respectively. This disparity in survival rates may be influenced by the inherent characteristics of these bacteria, available nutrients as well as the stages of the anaerobic digestion process. In addition, the highest p-value i.e., 0.957 for E. coli showed the statistical significance of its model and the strongest correlation between its reductions with days of digestion. In conclusion, the results demonstrated that the specific bacterial pathogens in manure can be considerably reduced through anaerobic digestion after 133 days. PMID:25026086

  12. Major histocompatibility complex based resistance to a common bacterial pathogen of amphibians.

    PubMed

    Barribeau, Seth M; Villinger, Jandouwe; Waldman, Bruce

    2008-07-16

    Given their well-developed systems of innate and adaptive immunity, global population declines of amphibians are particularly perplexing. To investigate the role of the major histocompatibility complex (MHC) in conferring pathogen resistance, we challenged Xenopus laevis tadpoles bearing different combinations of four MHC haplotypes (f, g, j, and r) with the bacterial pathogen Aeromonas hydrophila in two experiments. In the first, we exposed ff, fg, gg, gj, and jj tadpoles, obtained from breeding MHC homozygous parents, to one of three doses of A. hydrophila or heat-killed bacteria as a control. In the second, we exposed ff, fg, fr, gg, rg, and rr tadpoles, obtained from breeding MHC heterozygous parents and subsequently genotyped by PCR, to A. hydrophila, heat-killed bacteria or media alone as controls. We thereby determined whether the same patterns of MHC resistance emerged within as among families, independent of non-MHC heritable differences. Tadpoles with r or g MHC haplotypes were more likely to die than were those with f or j haplotypes. Growth rates varied among MHC types, independent of exposure dose. Heterozygous individuals with both susceptible and resistant haplotypes were intermediate to either homozygous genotype in both size and survival. The effect of the MHC on growth and survival was consistent between experiments and across families. MHC alleles differentially confer resistance to, or tolerance of, the bacterial pathogen, which affects tadpoles' growth and survival.

  13. An Overview of the Control of Bacterial Pathogens in Cattle Manure.

    PubMed

    Manyi-Loh, Christy E; Mamphweli, Sampson N; Meyer, Edson L; Makaka, Golden; Simon, Michael; Okoh, Anthony I

    2016-08-25

    Cattle manure harbors microbial constituents that make it a potential source of pollution in the environment and infections in humans. Knowledge of, and microbial assessment of, manure is crucial in a bid to prevent public health and environmental hazards through the development of better management practices and policies that should govern manure handling. Physical, chemical and biological methods to reduce pathogen population in manure do exist, but are faced with challenges such as cost, odor pollution, green house gas emission, etc. Consequently, anaerobic digestion of animal manure is currently one of the most widely used treatment method that can help to salvage the above-mentioned adverse effects and in addition, produces biogas that can serve as an alternative/complementary source of energy. However, this method has to be monitored closely as it could be fraught with challenges during operation, caused by the inherent characteristics of the manure. In addition, to further reduce bacterial pathogens to a significant level, anaerobic digestion can be combined with other methods such as thermal, aerobic and physical methods. In this paper, we review the bacterial composition of cattle manure as well as methods engaged in the control of pathogenic microbes present in manure and recommendations that need to be respected and implemented in order to prevent microbial contamination of the environment, animals and humans.

  14. Directed antigen delivery as a vaccine strategy for an intracellular bacterial pathogen

    NASA Astrophysics Data System (ADS)

    Bouwer, H. G. Archie; Alberti-Segui, Christine; Montfort, Megan J.; Berkowitz, Nathan D.; Higgins, Darren E.

    2006-03-01

    We have developed a vaccine strategy for generating an attenuated strain of an intracellular bacterial pathogen that, after uptake by professional antigen-presenting cells, does not replicate intracellularly and is readily killed. However, after degradation of the vaccine strain within the phagolysosome, target antigens are released into the cytosol for endogenous processing and presentation for stimulation of CD8+ effector T cells. Applying this strategy to the model intracellular pathogen Listeria monocytogenes, we show that an intracellular replication-deficient vaccine strain is cleared rapidly in normal and immunocompromised animals, yet antigen-specific CD8+ effector T cells are stimulated after immunization. Furthermore, animals immunized with the intracellular replication-deficient vaccine strain are resistant to lethal challenge with a virulent WT strain of L. monocytogenes. These studies suggest a general strategy for developing safe and effective, attenuated intracellular replication-deficient vaccine strains for stimulation of protective immune responses against intracellular bacterial pathogens. CD8+ T cell | replication-deficient | Listeria monocytogenes

  15. Vector-Borne Bacterial Plant Pathogens: Interactions with Hemipteran Insects and Plants.

    PubMed

    Perilla-Henao, Laura M; Casteel, Clare L

    2016-01-01

    Hemipteran insects are devastating pests of crops due to their wide host range, rapid reproduction, and ability to transmit numerous plant-infecting pathogens as vectors. While the field of plant-virus-vector interactions has flourished in recent years, plant-bacteria-vector interactions remain poorly understood. Leafhoppers and psyllids are by far the most important vectors of bacterial pathogens, yet there are still significant gaps in our understanding of their feeding behavior, salivary secretions, and plant responses as compared to important viral vectors, such as whiteflies and aphids. Even with an incomplete understanding of plant-bacteria-vector interactions, some common themes have emerged: (1) all known vector-borne bacteria share the ability to propagate in the plant and insect host; (2) particular hemipteran families appear to be incapable of transmitting vector-borne bacteria; (3) all known vector-borne bacteria have highly reduced genomes and coding capacity, resulting in host-dependence; and (4) vector-borne bacteria encode proteins that are essential for colonization of specific hosts, though only a few types of proteins have been investigated. Here, we review the current knowledge on important vector-borne bacterial pathogens, including Xylella fastidiosa, Spiroplasma spp., Liberibacter spp., and 'Candidatus Phytoplasma spp.'. We then highlight recent approaches used in the study of vector-borne bacteria. Finally, we discuss the application of this knowledge for control and future directions that will need to be addressed in the field of vector-plant-bacteria interactions.

  16. Major Histocompatibility Complex Based Resistance to a Common Bacterial Pathogen of Amphibians

    PubMed Central

    Barribeau, Seth M.; Villinger, Jandouwe; Waldman, Bruce

    2008-01-01

    Given their well-developed systems of innate and adaptive immunity, global population declines of amphibians are particularly perplexing. To investigate the role of the major histocompatibilty complex (MHC) in conferring pathogen resistance, we challenged Xenopus laevis tadpoles bearing different combinations of four MHC haplotypes (f, g, j, and r) with the bacterial pathogen Aeromonas hydrophila in two experiments. In the first, we exposed ff, fg, gg, gj, and jj tadpoles, obtained from breeding MHC homozygous parents, to one of three doses of A. hydrophila or heat-killed bacteria as a control. In the second, we exposed ff, fg, fr, gg, rg, and rr tadpoles, obtained from breeding MHC heterozygous parents and subsequently genotyped by PCR, to A. hydrophila, heat-killed bacteria or media alone as controls. We thereby determined whether the same patterns of MHC resistance emerged within as among families, independent of non-MHC heritable differences. Tadpoles with r or g MHC haplotypes were more likely to die than were those with f or j haplotypes. Growth rates varied among MHC types, independent of exposure dose. Heterozygous individuals with both susceptible and resistant haplotypes were intermediate to either homozygous genotype in both size and survival. The effect of the MHC on growth and survival was consistent between experiments and across families. MHC alleles differentially confer resistance to, or tolerance of, the bacterial pathogen, which affects tadpoles' growth and survival. PMID:18629002

  17. Vector-Borne Bacterial Plant Pathogens: Interactions with Hemipteran Insects and Plants

    PubMed Central

    Perilla-Henao, Laura M.; Casteel, Clare L.

    2016-01-01

    Hemipteran insects are devastating pests of crops due to their wide host range, rapid reproduction, and ability to transmit numerous plant-infecting pathogens as vectors. While the field of plant–virus–vector interactions has flourished in recent years, plant–bacteria–vector interactions remain poorly understood. Leafhoppers and psyllids are by far the most important vectors of bacterial pathogens, yet there are still significant gaps in our understanding of their feeding behavior, salivary secretions, and plant responses as compared to important viral vectors, such as whiteflies and aphids. Even with an incomplete understanding of plant–bacteria–vector interactions, some common themes have emerged: (1) all known vector-borne bacteria share the ability to propagate in the plant and insect host; (2) particular hemipteran families appear to be incapable of transmitting vector-borne bacteria; (3) all known vector-borne bacteria have highly reduced genomes and coding capacity, resulting in host-dependence; and (4) vector-borne bacteria encode proteins that are essential for colonization of specific hosts, though only a few types of proteins have been investigated. Here, we review the current knowledge on important vector-borne bacterial pathogens, including Xylella fastidiosa, Spiroplasma spp., Liberibacter spp., and ‘Candidatus Phytoplasma spp.’. We then highlight recent approaches used in the study of vector-borne bacteria. Finally, we discuss the application of this knowledge for control and future directions that will need to be addressed in the field of vector–plant–bacteria interactions. PMID:27555855

  18. Animals devoid of pulmonary system as infection models in the study of lung bacterial pathogens.

    PubMed

    López Hernández, Yamilé; Yero, Daniel; Pinos-Rodríguez, Juan M; Gibert, Isidre

    2015-01-01

    Biological disease models can be difficult and costly to develop and use on a routine basis. Particularly, in vivo lung infection models performed to study lung pathologies use to be laborious, demand a great time and commonly are associated with ethical issues. When infections in experimental animals are used, they need to be refined, defined, and validated for their intended purpose. Therefore, alternative and easy to handle models of experimental infections are still needed to test the virulence of bacterial lung pathogens. Because non-mammalian models have less ethical and cost constraints as a subjects for experimentation, in some cases would be appropriated to include these models as valuable tools to explore host-pathogen interactions. Numerous scientific data have been argued to the more extensive use of several kinds of alternative models, such as, the vertebrate zebrafish (Danio rerio), and non-vertebrate insects and nematodes (e.g., Caenorhabditis elegans) in the study of diverse infectious agents that affect humans. Here, we review the use of these vertebrate and non-vertebrate models in the study of bacterial agents, which are considered the principal causes of lung injury. Curiously none of these animals have a respiratory system as in air-breathing vertebrates, where respiration takes place in lungs. Despite this fact, with the present review we sought to provide elements in favor of the use of these alternative animal models of infection to reveal the molecular signatures of host-pathogen interactions.

  19. Putrescine regulating by stress-responsive MAPK cascade contributes to bacterial pathogen defense in Arabidopsis.

    PubMed

    Kim, Su-Hyun; Kim, Sun-Hwa; Yoo, Seung-Jin; Min, Kwang-Hyun; Nam, Seung-Hee; Cho, Baik Ho; Yang, Kwang-Yeol

    2013-08-09

    Polyamines in plants are involved in various physiological and developmental processes including abiotic and biotic stress responses. We investigated the expression of ADCs, which are key enzymes in putrescine (Put) biosynthesis, and roles of Put involving defense response in Arabidopsis. The increased expression of ADC1 and ADC2, and the induction of Put were detected in GVG-NtMEK2(DD) transgenic Arabidopsis, whereas, their performance was partially compromised in GVG-NtMEK2(DD)/mpk3 and GVG-NtMEK2(DD)/mpk6 mutant following DEX treatment. The expression of ADC2 was highly induced by Pst DC3000 inoculation, while the transcript levels of ADC1 were slightly up-regulated. Compared to the WT plant, Put content in the adc2 knock-out mutant was reduced after Pst DC3000 inoculation, and showed enhanced susceptibility to pathogen infection. The adc2 mutant exhibited reduced expression of PR-1 after bacterial infection and the growth of the pathogen was about 4-fold more than that in the WT plant. Furthermore, the disease susceptibility of the adc2 mutant was recovered by the addition of exogenous Put. Taken together, these results suggest that Arabidopsis MPK3 and MPK6 play a positive role in the regulation of Put biosynthesis, and that Put contributes to bacterial pathogen defense in Arabidopsis.

  20. Animals devoid of pulmonary system as infection models in the study of lung bacterial pathogens

    PubMed Central

    López Hernández, Yamilé; Yero, Daniel; Pinos-Rodríguez, Juan M.; Gibert, Isidre

    2015-01-01

    Biological disease models can be difficult and costly to develop and use on a routine basis. Particularly, in vivo lung infection models performed to study lung pathologies use to be laborious, demand a great time and commonly are associated with ethical issues. When infections in experimental animals are used, they need to be refined, defined, and validated for their intended purpose. Therefore, alternative and easy to handle models of experimental infections are still needed to test the virulence of bacterial lung pathogens. Because non-mammalian models have less ethical and cost constraints as a subjects for experimentation, in some cases would be appropriated to include these models as valuable tools to explore host–pathogen interactions. Numerous scientific data have been argued to the more extensive use of several kinds of alternative models, such as, the vertebrate zebrafish (Danio rerio), and non-vertebrate insects and nematodes (e.g., Caenorhabditis elegans) in the study of diverse infectious agents that affect humans. Here, we review the use of these vertebrate and non-vertebrate models in the study of bacterial agents, which are considered the principal causes of lung injury. Curiously none of these animals have a respiratory system as in air-breathing vertebrates, where respiration takes place in lungs. Despite this fact, with the present review we sought to provide elements in favor of the use of these alternative animal models of infection to reveal the molecular signatures of host–pathogen interactions. PMID:25699030

  1. Short chain and polyunsaturated fatty acids in host gut health and foodborne bacterial pathogen inhibition.

    PubMed

    Peng, Mengfei; Biswas, Debabrata

    2017-12-12

    As a major source of microbes and their numerous beneficial effects, the gut microflora/microbiome is intimately linked to human health and disease. The exclusion of enteric pathogens by these commensal microbes partially depends upon the production of bioactive compounds such as short-chain fatty acids (SCFAs) and polyunsaturated fatty acids (PUFAs). These key intestinal microbial byproducts are crucial to the maintenance of a healthy gut microbial community. Moreover, SCFAs and PUFAs play multiple critical roles in host defense and immunity, including anti-cancer, anti-inflammation, and anti-oxidant activities, as well as out-competition of enteric bacterial pathogens. In this review article, we hereby aim to highlight the importance of SCFAs and PUFAs and the microbes involved in production of these beneficial intestinal components, and their biological functions, specifically as to their immunomodulation and interactions with enteric bacterial pathogens. Finally, we also advance potential applications of these fatty acids with regards to food safety and human gut health.

  2. Rate enhancement of bacterial extracellular electron transport involves bound flavin semiquinones

    PubMed Central

    Okamoto, Akihiro; Hashimoto, Kazuhito; Nealson, Kenneth H.; Nakamura, Ryuhei

    2013-01-01

    Extracellular redox-active compounds, flavins and other quinones, have been hypothesized to play a major role in the delivery of electrons from cellular metabolic systems to extracellular insoluble substrates by a diffusion-based shuttling two-electron-transfer mechanism. Here we show that flavin molecules secreted by Shewanella oneidensis MR-1 enhance the ability of its outer-membrane c-type cytochromes (OM c-Cyts) to transport electrons as redox cofactors, but not free-form flavins. Whole-cell differential pulse voltammetry revealed that the redox potential of flavin was reversibly shifted more than 100 mV in a positive direction, in good agreement with increasing microbial current generation. Importantly, this flavin/OM c-Cyts interaction was found to facilitate a one-electron redox reaction via a semiquinone, resulting in a 103- to 105-fold faster reaction rate than that of free flavin. These results are not consistent with previously proposed redox-shuttling mechanisms but suggest that the flavin/OM c-Cyts interaction regulates the extent of extracellular electron transport coupled with intracellular metabolic activity. PMID:23576738

  3. The autofluorescence characteristics of bacterial intracellular and extracellular substances during the operation of anammox reactor

    PubMed Central

    Hou, Xiaolin; Liu, Sitong; Feng, Ying

    2017-01-01

    Anammox is a cost-effective process to treat nitrogenous wastewater. In this work, excitation–emission matrix (EEM) fluorescence spectroscopy was used to characterize the intracellular and extracellular substances of anammox sludge during reactor operation of 276 days. Four main fluorophores were identified from the intracellular substances. Two main protein-like fluorophores were identified from the extracellular substances. Correlation analysis revealed that intracellular 420 peak and humic-like peak had strong correlation with nitrogen removal rate. The two intracellular protein-like peaks had high correlation with MLVSS and MLVSS growth rate. Correlation analysis between different fluorophores discovered that the two peaks in each of these three groups—two intracellular protein-like peaks, two humic acid-like peaks and the two extracellular protein-like peaks had strong intercorrelation, which gave evidence of their homology. A specific method for fluorescence monitoring of anammox reactor were put forward, which included typical fluorescence indexes and their possible values for different operation phases. PMID:28091530

  4. Estimation of decay rates for fecal indicator bacteria and bacterial pathogens in agricultural field-applied manure

    EPA Science Inventory

    Field-applied manure is an important source of pathogenic exposure in surface water bodies for humans and ecological receptors. We analyzed the persistence and decay of fecal indicator bacteria and bacterial pathogens from three sources (cattle, poultry, swine) for agricultural f...

  5. Estimation of decay rates for fecal indicator bacteria and bacterial pathogens in agricultural field-applied manure

    EPA Science Inventory

    Field-applied manure is an important source of pathogenic exposure in surface water bodies for humans and ecological receptors. We analyzed the persistence and decay of fecal indicator bacteria and bacterial pathogens from three sources (cattle, poultry, swine) for agricultural f...

  6. Diversity of both the cultivable protease-producing bacteria and bacterial extracellular proteases in the coastal sediments of King George Island, Antarctica.

    PubMed

    Zhou, Ming-Yang; Wang, Guang-Long; Li, Dan; Zhao, Dian-Li; Qin, Qi-Long; Chen, Xiu-Lan; Chen, Bo; Zhou, Bai-Cheng; Zhang, Xi-Ying; Zhang, Yu-Zhong

    2013-01-01

    Protease-producing bacteria play a vital role in degrading sedimentary organic nitrogen. However, the diversity of these bacteria and their extracellular proteases in most regions remain unknown. In this paper, the diversity of the cultivable protease-producing bacteria and of bacterial extracellular proteases in the sediments of Maxwell Bay, King George Island, Antarctica was investigated. The cultivable protease-producing bacteria reached 10(5) cells/g in all 8 sediment samples. The cultivated protease-producing bacteria were mainly affiliated with the phyla Actinobacteria, Firmicutes, Bacteroidetes, and Proteobacteria, and the predominant genera were Bacillus (22.9%), Flavobacterium (21.0%) and Lacinutrix (16.2%). Among these strains, Pseudoalteromonas and Flavobacteria showed relatively high protease production. Inhibitor analysis showed that nearly all the extracellular proteases from the bacteria were serine proteases or metalloproteases. These results begin to address the diversity of protease-producing bacteria and bacterial extracellular proteases in the sediments of the Antarctic Sea.

  7. Investigation of extracellular polymeric substances (EPS) properties of P. aeruginosa and B. subtilis and their role in bacterial adhesion.

    PubMed

    Harimawan, Ardiyan; Ting, Yen-Peng

    2016-10-01

    Extracellular polymeric substances (EPS) matrix in biofilm poses important functions such as a diffusion barrier to antimicrobial agents so that biofilm cells are more difficult to completely eliminate. Therefore, biofilm cells exhibit enhanced resilience unlike planktonic cells, and are more difficult to completely eliminate. In order to obtain a comprehensive understanding of bacterial adhesion to surfaces, knowledge of the composition and conformational properties of EPS produced during growth and biofilm formation is required, since their adhesive and conformational properties remain poorly understood at molecular level. Present study has provided further insights into identifying compositional and conformational properties of EPS produced by planktonic and biofilm cells of B. subtilis and P. aeruginosa. Various spectroscopy analyses showed that EPS produced by the two different species were chemically dissimilar. More proteinaceous compounds were present in EPS from B. subtilis, while EPS from P. aeruginosa were characterized by greater carbohydrate components. However, relative proportions of polysaccharides and/or proteins constituents varied with the growth mode of the bacteria. AFM was then used to probe the adhesive nature of EPS produced by the bacteria by using Single Molecule Force Spectroscopy (SMFS). Comparison of the two bacterial species indicated that the presence of polysaccharides promoted the adhesion strength of the EPS while proteins had lesser adherence effects. Comparison of the two growth modes for the same bacterial strain also indicated that greater EPS production and enhanced cellular adhesion are associated with biofilm growth.

  8. Tolerance to lipopolysaccharide promotes an enhanced neutrophil extracellular traps formation leading to a more efficient bacterial clearance in mice

    PubMed Central

    Landoni, V I; Chiarella, P; Martire-Greco, D; Schierloh, P; van-Rooijen, N; Rearte, B; Palermo, M S; Isturiz, M A; Fernández, G C

    2012-01-01

    Tolerance to lipopolysaccharide (LPS) constitutes a stress adaptation, in which a primary contact with LPS results in a minimal response when a second exposure with the same stimulus occurs. However, active important defence mechanisms are mounted during the tolerant state. Our aim was to assess the contribution of polymorphonuclear neutrophils (PMN) in the clearance of bacterial infection in a mouse model of tolerance to LPS. After tolerance was developed, we investigated in vivo different mechanisms of bacterial clearance. The elimination of a locally induced polymicrobial challenge was more efficient in tolerant mice both in the presence or absence of local macrophages. This was related to a higher number of PMN migrating to the infectious site as a result of an increased number of PMN from the marginal pool with higher chemotactic capacity, not because of differences in their phagocytic activity or reactive species production. In vivo, neutrophils extracellular trap (NET) destruction by nuclease treatment abolished the observed increased clearance in tolerant but not in control mice. In line with this finding, in vitro NETs formation was higher in PMN from tolerant animals. These results indicate that the higher chemotactic response from an increased PMN marginal pool and the NETs enhanced forming capacity are the main mechanisms mediating bacterial clearance in tolerant mice. To sum up, far from being a lack of response, tolerance to LPS causes PMN priming effects which favour distant and local anti-infectious responses. PMID:22385250

  9. Differential induction of redox sensitive extracellular phenolic amides in potato

    USDA-ARS?s Scientific Manuscript database

    This study focuses on the differential induction of extracellular phenolic amides that accumulate in potato cell suspensions during the first few hours of the interaction between these plant cells and bacterial pathogens or pathogen-related elicitors. Using suspension cells of Solanum tuberosum we ...

  10. Factors related to occurrence and distribution of selected bacterial and protozoan pathogens in Pennsylvania streams

    USGS Publications Warehouse

    Duris, Joseph W.; Reif, Andrew G.; Donna A. Crouse,; Isaacs, Natasha M.

    2013-01-01

    The occurrence and distribution of fecal indicator bacteria (FIB) and bacterial and protozoan pathogens are controlled by diverse factors. To investigate these factors in Pennsylvania streams, 217 samples were collected quarterly from a 27-station water-quality monitoring network from July 2007 through August 2009. Samples were analyzed for concentrations of Escherichia coli (EC) and enterococci (ENT) indicator bacteria, concentrations of Cryptosporidium oocysts and Giardia cysts, and the presence of four genes related to pathogenic types of EC (eaeA, stx2, stx1, rfbO157) plus three microbial source tracking (MST) gene markers that are also associated with pathogenic ENT and EC (esp, LTIIa, STII). Water samples were concurrently analyzed for basic water chemistry, physical measures of water quality, nutrients, metals, and a suite of 79 organic compounds that included hormones, pharmaceuticals, and antibiotics. For each sample location, stream discharge was measured by using standardized methods at the time of sample collection, and ancillary sample site information, such as land use and geological characteristics, was compiled. Samples exceeding recreational water quality criteria were more likely to contain all measured pathogen genes but notCryptosporidium or Giardia (oo)cysts. FIB and Giardia density and frequency of eaeA gene occurrence were significantly related to season. When discharge at a sampling location was high (>75th percentile of daily mean discharge), there were greater densities of FIB and Giardia, and the stx2, rfbO157, STII, and esp genes were found more frequently than at other discharge conditions. Giardia occurrence was likely related to nonpoint sources, which are highly influential during seasonal overland transport resulting from snowmelt and elevated precipitation in late winter and spring in Pennsylvania. When MST markers of human, swine, or bovine origin were present, samples more frequently carried the eaeA, stx2

  11. Scalable economic extracellular synthesis of CdS nanostructured particles by a non-pathogenic thermophile

    SciTech Connect

    Moon, Ji Won; Ivanov, Ilia N; Duty, Chad E; Love, Lonnie J; Rondinone, Adam Justin; Wang, Wei; Li, Dr. Yi-Liang; Madden, Andrew; Mosher, Jennifer J; Hu, Michael Z.; Suresh, Anil K; Rawn, Claudia J; Jung, Hyunsung; Lauf, Robert J; Phelps, Tommy Joe

    2013-01-01

    We report microbially facilitated synthesis of cadmium sulfide (CdS) nanostructured particles (NP) using anaerobic, metal-reducing Thermoanaerobacter sp. The extracellular CdS crystallites were <10 nm in size with yields of ~3 g/L of growth medium/month with demonstrated reproducibility and scalability up to 24 L. During synthesis, Thermoanaerobacter cultures reduced thiosulfate and sulfite salts to H2S, which reacted with Cd2+ cations to produce thermodynamically favored NP in a single step at 65oC with catalytic nucleation on the cell surfaces. Photoluminescence (PL) analysis of dry CdS NP revealed an exciton-dominated PL peak at 440 nm, having a narrow full width at half maximum of 10 nm. A PL spectrum of CdS NP produced by dissimilatory sulfur reducing bacteria was dominated by features associated with radiative exciton relaxation at the surface. High reproducibility of CdS NP PL features important for scale-up conditions was confirmed from test tubes to 24L batches at a small fraction of the manufacturing cost associated with conventional inorganic NP production processes.

  12. Nanobacteria: An alternative mechanism for pathogenic intra- and extracellular calcification and stone formation

    PubMed Central

    Kajander, E. Olavi; Çiftçioglu, Neva

    1998-01-01

    Calcium phosphate is deposited in many diseases, but formation mechanisms remain speculative. Nanobacteria are the smallest cell-walled bacteria, only recently discovered in human and cow blood and commercial cell culture serum. In this study, we identified with energy-dispersive x-ray microanalysis and chemical analysis that all growth phases of nanobacteria produce biogenic apatite on their cell envelope. Fourier transform IR spectroscopy revealed the mineral as carbonate apatite. The biomineralization in cell culture media resulted in biofilms and mineral aggregates closely resembling those found in tissue calcification and kidney stones. In nanobacteria-infected fibroblasts, electron microscopy revealed intra- and extracellular acicular crystal deposits, stainable with von Kossa staining and resembling calcospherules found in pathological calcification. Previous models for stone formation have led to an hypothesis that elevated pH due to urease and/or alkaline phosphatase activity is a lithogenic factor. Our results indicate that carbonate apatite can be formed without these factors at pH 7.4, at physiological phosphate and calcium concentrations. Nanobacteria can produce apatite in media mimicking tissue fluids and glomerular filtrate and provide a unique model for in vitro studies on calcification. PMID:9653177

  13. Nanobacteria: an alternative mechanism for pathogenic intra- and extracellular calcification and stone formation.

    PubMed

    Kajander, E O; Ciftçioglu, N

    1998-07-07

    Calcium phosphate is deposited in many diseases, but formation mechanisms remain speculative. Nanobacteria are the smallest cell-walled bacteria, only recently discovered in human and cow blood and commercial cell culture serum. In this study, we identified with energy-dispersive x-ray microanalysis and chemical analysis that all growth phases of nanobacteria produce biogenic apatite on their cell envelope. Fourier transform IR spectroscopy revealed the mineral as carbonate apatite. The biomineralization in cell culture media resulted in biofilms and mineral aggregates closely resembling those found in tissue calcification and kidney stones. In nanobacteria-infected fibroblasts, electron microscopy revealed intra- and extracellular acicular crystal deposits, stainable with von Kossa staining and resembling calcospherules found in pathological calcification. Previous models for stone formation have led to an hypothesis that elevated pH due to urease and/or alkaline phosphatase activity is a lithogenic factor. Our results indicate that carbonate apatite can be formed without these factors at pH 7.4, at physiological phosphate and calcium concentrations. Nanobacteria can produce apatite in media mimicking tissue fluids and glomerular filtrate and provide a unique model for in vitro studies on calcification.

  14. Detection of human bacterial pathogens in ticks collected from Louisiana black bears (Ursus americanus luteolus).

    PubMed

    Leydet, Brian F; Liang, Fang-Ting

    2013-04-01

    There are 4 major human-biting tick species in the northeastern United States, which include: Amblyomma americanum, Amblyomma maculatum, Dermacentor variabilis, and Ixodes scapularis. The black bear is a large mammal that has been shown to be parasitized by all the aforementioned ticks. We investigated the bacterial infections in ticks collected from Louisiana black bears (Ursus americanus subspecies luteolus). Eighty-six ticks were collected from 17 black bears in Louisiana from June 2010 to March 2011. All 4 common human-biting tick species were represented. Each tick was subjected to polymerase chain reaction (PCR) targeting select bacterial pathogens and symbionts. Bacterial DNA was detected in 62% of ticks (n=53). Rickettsia parkeri, the causative agent of an emerging spotted fever group rickettsiosis, was identified in 66% of A. maculatum, 28% of D. variabilis, and 11% of I. scapularis. The Lyme disease bacterium, Borrelia burgdorferi, was detected in 2 I. scapularis, while one A. americanum was positive for Borrelia bissettii, a putative human pathogen. The rickettsial endosymbionts Candidatus Rickettsia andeanae, rickettsial endosymbiont of I. scapularis, and Rickettsia amblyommii were detected in their common tick hosts at 21%, 39%, and 60%, respectively. All ticks were PCR-negative for Anaplasma phagocytophilum, Ehrlichia spp., and Babesia microti. This is the first reported detection of R. parkeri in vector ticks in Louisiana; we also report the novel association of R. parkeri with I. scapularis. Detection of both R. parkeri and B. burgdorferi in their respective vectors in Louisiana demands further investigation to determine potential for human exposure to these pathogens. Copyright © 2013 Elsevier GmbH. All rights reserved.

  15. Immune Subversion and Quorum-Sensing Shape the Variation in Infectious Dose among Bacterial Pathogens

    PubMed Central

    Gama, João Alves; Abby, Sophie S.; Vieira-Silva, Sara; Dionisio, Francisco; Rocha, Eduardo P. C.

    2012-01-01

    Many studies have been devoted to understand the mechanisms used by pathogenic bacteria to exploit human hosts. These mechanisms are very diverse in the detail, but share commonalities whose quantification should enlighten the evolution of virulence from both a molecular and an ecological perspective. We mined the literature for experimental data on infectious dose of bacterial pathogens in humans (ID50) and also for traits with which ID50 might be associated. These compilations were checked and complemented with genome analyses. We observed that ID50 varies in a continuous way by over 10 orders of magnitude. Low ID50 values are very strongly associated with the capacity of the bacteria to kill professional phagocytes or to survive in the intracellular milieu of these cells. Inversely, high ID50 values are associated with motile and fast-growing bacteria that use quorum-sensing based regulation of virulence factors expression. Infectious dose is not associated with genome size and shows insignificant phylogenetic inertia, in line with frequent virulence shifts associated with the horizontal gene transfer of a small number of virulence factors. Contrary to previous proposals, infectious dose shows little dependence on contact-dependent secretion systems and on the natural route of exposure. When all variables are combined, immune subversion and quorum-sensing are sufficient to explain two thirds of the variance in infectious dose. Our results show the key role of immune subversion in effective human infection by small bacterial populations. They also suggest that cooperative processes might be important for successful infection by bacteria with high ID50. Our results suggest that trade-offs between selection for population growth-related traits and selection for the ability to subvert the immune system shape bacterial infectiousness. Understanding these trade-offs provides guidelines to study the evolution of virulence and in particular the micro-evolutionary paths

  16. Bacteriocin from Bacillus subtilis as a novel drug against diabetic foot ulcer bacterial pathogens.

    PubMed

    Joseph, Baby; Dhas, Berlina; Hena, Vimalin; Raj, Justin

    2013-12-01

    To isolate and identify Bacillus subtilis (B. subtilis) from soil and to characterize and partially purify the bacteriocin. To evaluate the antimicrobial activity against four diabetic foot ulcer bacterial pathogens. Genotypic identification was done based on Bergey's manual of systemic bacteriology. Antimicrobial susceptibility test was done by Kirby-Bauer disc diffusion method. Colonies were identified by colony morphology and biochemical characterization and also compared with MTCC 121 strain. Further identification was done by 16S rRNA sequencing. Inhibitory activities of partially purified bacteriocin on all the DFU isolates were done by agar well diffusion method. The strain was identified to produce bacteriocin by stab overlay assay. Bacteriocin was extracted by organic solvent extraction using chloroform, further purified by HPLC and physical, and chemical characterization was performed. The four isolates showed high level of resistance to amoxyclav and sensitivity to ciprofloxacin. HPLC purification revealed that the extracts are bacteriocin. The phylogenetic tree analysis results showed that the isolate was 99% related to B. subtilis BSF01. The results reveled activity to all the four isolates and high level of activity was seen in case of Klebsiella sp. Partially purified bacteriocin was found to have antimicrobial activity against the four diabetic foot ulcer bacterial pathogens, which can thus be applied as a better drug molecule on further studies. The strain B. subtilis are found to be safe for use and these antimicrobial peptides can be used as an antimicrobial in humans to treat DFU bacterial pathogens. Copyright © 2013 Asian Pacific Tropical Biomedical Magazine. Published by Elsevier B.V. All rights reserved.

  17. Fecal indicators and bacterial pathogens in bottled water from Dhaka, Bangladesh

    PubMed Central

    Ahmed, W.; Yusuf, R.; Hasan, I.; Ashraf, W.; Goonetilleke, A.; Toze, S.; Gardner, T.

    2013-01-01

    Forty-six bottled water samples representing 16 brands from Dhaka, Bangladesh were tested for the numbers of total coliforms, fecal indicator bacteria (i.e., thermotolerant Escherichia coli and Enterococcus spp.) and potential bacterial pathogens (i.e., Aeromonas hydrophila, Pseudomonas aeruginosa, Salmonella spp., and Shigella spp.). Among the 16 brands tested, 14 (86%), ten (63%) and seven (44%) were positive for total coliforms, E. coil and Enterococcus spp., respectively. Additionally, a further nine (56%), eight (50%), six (37%), and four (25%) brands were PCR positive for A. hydrophila lip, P. aeruginosa ETA, Salmonella spp. invA, and Shigella spp. ipaH genes, respectively. The numbers of bacterial pathogens in bottled water samples ranged from 28 ± 12 to 600 ± 45 (A. hydrophila lip gene), 180 ± 40 to 900 ± 200 (Salmonella spp. invA gene), 180 ± 40 to 1,300 ± 400 (P. aeruginosa ETA gene) genomic units per L of water. Shigella spp. ipaH gene was not quantifiable. Discrepancies were observed in terms of the occurrence of fecal indicators and bacterial pathogens. No correlations were observed between fecal indicators numbers and presence/absence of A. hydrophila lip (p = 0.245), Salmonella spp. invA (p = 0.433), Shigella spp. ipaH gene (p = 0.078), and P. aeruginosa ETA (p = 0.059) genes. Our results suggest that microbiological quality of bottled waters sold in Dhaka, Bangladesh is highly variable. To protect public health, stringent quality control is recommended for the bottled water industry in Bangladesh. PMID:24159289

  18. Cellulose as extracellular polysaccharide of hot spring sulfur-turf bacterial mat.

    PubMed

    Ogawa, Kazutoshi; Maki, Yonosuke

    2003-12-01

    The carbohydrate fraction of a hot spring sulfur-turf bacterial mat was shown to contain cellulose by the examination of neutral sugar composition, methylation analysis, and the identification of free oligosacchrides obtained from an acetolyzate of the desulfurized sulfur-turf mat. This suggested that the sulfur-oxidizing bacteria composing the sulfur-turf were producers of cellulose.

  19. In Vitro Activity of Delafloxacin against Contemporary Bacterial Pathogens from the United States and Europe, 2014

    PubMed Central

    Pfaller, M. A.; Sader, H. S.; Rhomberg, P. R.

    2017-01-01

    ABSTRACT The in vitro activities of delafloxacin and comparator antimicrobial agents against 6,485 bacterial isolates collected from medical centers in Europe and the United States in 2014 were tested. Delafloxacin was the most potent agent tested against methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-resistant S. aureus, Streptococcus pneumoniae, viridans group streptococci, and beta-hemolytic streptococci and had activity similar to that of ciprofloxacin and levofloxacin against certain members of the Enterobacteriaceae. Overall, the broadest coverage of the tested pathogens (Gram-positive cocci and Gram-negative bacilli) was observed with meropenem and tigecycline in both Europe and the United States. Delafloxacin was shown to be active against organisms that may be encountered in acute bacterial skin and skin structure infections, respiratory infections, and urinary tract infections. PMID:28167542

  20. Enterobacter aerogenes and Enterobacter cloacae; versatile bacterial pathogens confronting antibiotic treatment

    PubMed Central

    Davin-Regli, Anne; Pagès, Jean-Marie

    2015-01-01

    Enterobacter aerogenes and E. cloacae have been reported as important opportunistic and multiresistant bacterial pathogens for humans during the last three decades in hospital wards. These Gram-negative bacteria have been largely described during several outbreaks of hospital-acquired infections in Europe and particularly in France. The dissemination of Enterobacter sp. is associated with the presence of redundant regulatory cascades that efficiently control the membrane permeability ensuring the bacterial protection and the expression of detoxifying enzymes involved in antibiotic degradation/inactivation. In addition, these bacterial species are able to acquire numerous genetic mobile elements that strongly contribute to antibiotic resistance. Moreover, this particular fitness help them to colonize several environments and hosts and rapidly and efficiently adapt their metabolism and physiology to external conditions and environmental stresses. Enterobacter is a versatile bacterium able to promptly respond to the antibiotic treatment in the colonized patient. The balance of the prevalence, E. aerogenes versus E. cloacae, in the reported hospital infections during the last period, questions about the horizontal transmission of mobile elements containing antibiotic resistance genes, e.g., the efficacy of the exchange of resistance genes Klebsiella pneumoniae to Enterobacter sp. It is also important to mention the possible role of antibiotic use in the treatment of bacterial infectious diseases in this E. aerogenes/E. cloacae evolution. PMID:26042091

  1. Enterobacter aerogenes and Enterobacter cloacae; versatile bacterial pathogens confronting antibiotic treatment.

    PubMed

    Davin-Regli, Anne; Pagès, Jean-Marie

    2015-01-01

    Enterobacter aerogenes and E. cloacae have been reported as important opportunistic and multiresistant bacterial pathogens for humans during the last three decades in hospital wards. These Gram-negative bacteria have been largely described during several outbreaks of hospital-acquired infections in Europe and particularly in France. The dissemination of Enterobacter sp. is associated with the presence of redundant regulatory cascades that efficiently control the membrane permeability ensuring the bacterial protection and the expression of detoxifying enzymes involved in antibiotic degradation/inactivation. In addition, these bacterial species are able to acquire numerous genetic mobile elements that strongly contribute to antibiotic resistance. Moreover, this particular fitness help them to colonize several environments and hosts and rapidly and efficiently adapt their metabolism and physiology to external conditions and environmental stresses. Enterobacter is a versatile bacterium able to promptly respond to the antibiotic treatment in the colonized patient. The balance of the prevalence, E. aerogenes versus E. cloacae, in the reported hospital infections during the last period, questions about the horizontal transmission of mobile elements containing antibiotic resistance genes, e.g., the efficacy of the exchange of resistance genes Klebsiella pneumoniae to Enterobacter sp. It is also important to mention the possible role of antibiotic use in the treatment of bacterial infectious diseases in this E. aerogenes/E. cloacae evolution.

  2. Origin and Proliferation of Multiple-Drug Resistance in Bacterial Pathogens

    PubMed Central

    Chang, Hsiao-Han; Cohen, Ted; Grad, Yonatan H.; Hanage, William P.; O'Brien, Thomas F.

    2015-01-01

    SUMMARY Many studies report the high prevalence of multiply drug-resistant (MDR) strains. Because MDR infections are often significantly harder and more expensive to treat, they represent a growing public health threat. However, for different pathogens, different underlying mechanisms are traditionally used to explain these observations, and it is unclear whether each bacterial taxon has its own mechanism(s) for multidrug resistance or whether there are common mechanisms between distantly related pathogens. In this review, we provide a systematic overview of the causes of the excess of MDR infections and define testable predictions made by each hypothetical mechanism, including experimental, epidemiological, population genomic, and other tests of these hypotheses. Better understanding the cause(s) of the excess of MDR is the first step to rational design of more effective interventions to prevent the origin and/or proliferation of MDR. PMID:25652543

  3. Staphylococcus aureus: is it a pathogen of acute bacterial sinusitis in children and adults?

    PubMed

    Wald, Ellen R

    2012-03-01

    Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis are the etiologic agents of acute bacterial sinusitis (ABS). Staphylococcus aureus has been an uncommon cause of ABS despite its frequent occupancy within the anterior nares. A quantitative culture of a maxillary sinus aspirate is the gold standard for determining etiology of ABS. Cultures of the middle meatus cannot be used as a surrogate for a maxillary sinus aspirate in children with ABS, although they may be used in adults if interpretation is confined to usual sinus pathogens. Recent studies highlighting S. aureus as a major pathogen in ABS should be interpreted cautiously. Most isolates in recent pediatric studies were derived from cultures of the middle meatus. The range of reported results for the incidence of S. aureus as a cause of ABS in adults is similar to the results reported for staphylococcal colonization of the middle meatus in healthy adults.

  4. Identification of bacterial and fungal pathogens from positive blood culture bottles: a microarray-based approach.

    PubMed

    Raich, Teresa; Powell, Scott

    2015-01-01

    Rapid identification and characterization of bacterial and fungal pathogens present in the bloodstream are essential for optimal patient management and are associated with improved patient outcomes, improved antimicrobial stewardship, improved infection control, and reduced healthcare costs. Microarrays serve as reliable platforms for the identification of these bloodstream pathogens and their associated antimicrobial resistance genes, if present. Nanosphere's (Nanosphere, Inc., Northbrook, IL, USA) Verigene Gram-Positive Blood Culture Nucleic-Acid Test (BC-GP) is one such microarray-based approach for the detection of bacteria that cause bloodstream infection. Here, we describe the design of the microarray-based Verigene BC-GP Test, the steps necessary for performing the test, and the different components of the test including nucleic acid extraction and hybridization of target nucleic acid to a microarray.

  5. Seagrass ecosystems reduce exposure to bacterial pathogens of humans, fishes, and invertebrates.

    PubMed

    Lamb, Joleah B; van de Water, Jeroen A J M; Bourne, David G; Altier, Craig; Hein, Margaux Y; Fiorenza, Evan A; Abu, Nur; Jompa, Jamaluddin; Harvell, C Drew

    2017-02-17

    Plants are important in urban environments for removing pathogens and improving water quality. Seagrass meadows are the most widespread coastal ecosystem on the planet. Although these plants are known to be associated with natural biocide production, they have not been evaluated for their ability to remove microbiological contamination. Using amplicon sequencing of the 16S ribosomal RNA gene, we found that when seagrass meadows are present, there was a 50% reduction in the relative abundance of potential bacterial pathogens capable of causing disease in humans and marine organisms. Moreover, field surveys of more than 8000 reef-building corals located adjacent to seagrass meadows showed twofold reductions in disease levels compared to corals at paired sites without adjacent seagrass meadows. These results highlight the importance of seagrass ecosystems to the health of humans and other organisms.

  6. Comparison of pathogenic and spoilage bacterial levels on refrigerated poultry parts following treatment with trisodium phosphate.

    PubMed

    del Río, Elena; Capita, Rosa; Prieto, Miguel; Alonso-Calleja, Carlos

    2006-04-01

    This study was undertaken to determine whether trisodium phosphate decontamination of poultry could give a competitive advantage to pathogens and increase microbiological risk to consumers. Chicken legs were co-inoculated with similar concentrations of pathogenic (Salmonella Enteritidis or Listeria monocytogenes) and spoilage (Pseudomonas fluorescens or Brochothrix thermosphacta) bacteria. Samples were dipped in TSP (12%, 15 min) or were non-treated (control). Microbiological analyses were carried out at 0, 1, 3 and 5 days of storage (3 degrees C). Levels of spoilage bacteria were higher than those of S. Enteritidis on both treated and non-treated legs. Similar bacterial loads were observed for L. monocytogenes and B. thermosphacta. However, P. fluorescens counts on TSP-treated samples were significantly lower than those of L. monocytogenes at all sampling times. Our results found that P. fluorescens (a spoilage organism) was more susceptible to TSP treatment than L. monocytogenes when inoculated at 10(6) cfu g(-1).

  7. Comparative Resistance of Bacterial Foodborne Pathogens to No