Granulocyte-macrophage colony stimulatory factor enhances the pro-inflammatory response of interferon-γ-treated macrophages to Pseudomonas aeruginosa infection.

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Sonali Singh

Full Text Available Pseudomonas aeruginosa is an opportunistic pathogen that can cause severe infections at compromised epithelial surfaces, such those found in burns, wounds, and in lungs damaged by mechanical ventilation or recurrent infections, particularly in cystic fibrosis (CF patients. CF patients have been proposed to have a Th2 and Th17-biased immune response suggesting that the lack of Th1 and/or over exuberant Th17 responses could contribute to the establishment of chronic P. aeruginosa infection and deterioration of lung function. Accordingly, we have observed that interferon (IFN-γ production by peripheral blood mononuclear cells from CF patients positively correlated with lung function, particularly in patients chronically infected with P. aeruginosa. In contrast, IL-17A levels tended to correlate negatively with lung function with this trend becoming significant in patients chronically infected with P. aeruginosa. These results are in agreement with IFN-γ and IL-17A playing protective and detrimental roles, respectively, in CF. In order to explore the protective effect of IFN-γ in CF, the effect of IFN-γ alone or in combination with granulocyte-macrophage colony-stimulating factor (GM-CSF, on the ability of human macrophages to control P. aeruginosa growth, resist the cytotoxicity induced by this bacterium or promote inflammation was investigated. Treatment of macrophages with IFN-γ, in the presence and absence of GM-CSF, failed to alter bacterial growth or macrophage survival upon P. aeruginosa infection, but changed the inflammatory potential of macrophages. IFN-γ caused up-regulation of monocyte chemoattractant protein-1 (MCP-1 and TNF-α and down-regulation of IL-10 expression by infected macrophages. GM-CSF in combination with IFN-γ promoted IL-6 production and further reduction of IL-10 synthesis. Comparison of TNF-α vs. IL-10 and IL-6 vs. IL-10 ratios revealed the following hierarchy in regard to the pro-inflammatory potential of human

Granulocyte-macrophage colony stimulatory factor enhances the pro-inflammatory response of interferon-γ-treated macrophages to Pseudomonas aeruginosa infection.

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Singh, Sonali; Barr, Helen; Liu, Yi-Chia; Robins, Adrian; Heeb, Stephan; Williams, Paul; Fogarty, Andrew; Cámara, Miguel; Martínez-Pomares, Luisa

2015-01-01

Pseudomonas aeruginosa is an opportunistic pathogen that can cause severe infections at compromised epithelial surfaces, such those found in burns, wounds, and in lungs damaged by mechanical ventilation or recurrent infections, particularly in cystic fibrosis (CF) patients. CF patients have been proposed to have a Th2 and Th17-biased immune response suggesting that the lack of Th1 and/or over exuberant Th17 responses could contribute to the establishment of chronic P. aeruginosa infection and deterioration of lung function. Accordingly, we have observed that interferon (IFN)-γ production by peripheral blood mononuclear cells from CF patients positively correlated with lung function, particularly in patients chronically infected with P. aeruginosa. In contrast, IL-17A levels tended to correlate negatively with lung function with this trend becoming significant in patients chronically infected with P. aeruginosa. These results are in agreement with IFN-γ and IL-17A playing protective and detrimental roles, respectively, in CF. In order to explore the protective effect of IFN-γ in CF, the effect of IFN-γ alone or in combination with granulocyte-macrophage colony-stimulating factor (GM-CSF), on the ability of human macrophages to control P. aeruginosa growth, resist the cytotoxicity induced by this bacterium or promote inflammation was investigated. Treatment of macrophages with IFN-γ, in the presence and absence of GM-CSF, failed to alter bacterial growth or macrophage survival upon P. aeruginosa infection, but changed the inflammatory potential of macrophages. IFN-γ caused up-regulation of monocyte chemoattractant protein-1 (MCP-1) and TNF-α and down-regulation of IL-10 expression by infected macrophages. GM-CSF in combination with IFN-γ promoted IL-6 production and further reduction of IL-10 synthesis. Comparison of TNF-α vs. IL-10 and IL-6 vs. IL-10 ratios revealed the following hierarchy in regard to the pro-inflammatory potential of human macrophages

Rugosity Derivative Surface used to characterize the complexity of the seafloor around St. John, USVI

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National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity was calculated from the bathymetry surface for each cell using the "Rugosity" function in the Benthic Terrain Modeler toolbox (Jenness 2002, 2004; Wright et...

Ginger Extract Inhibits Biofilm Formation by Pseudomonas aeruginosa PA14

Science.gov (United States)

Kim, Han-Shin; Park, Hee-Deung

2013-01-01

Bacterial biofilm formation can cause serious problems in clinical and industrial settings, which drives the development or screening of biofilm inhibitors. Some biofilm inhibitors have been screened from natural products or modified from natural compounds. Ginger has been used as a medicinal herb to treat infectious diseases for thousands of years, which leads to the hypothesis that it may contain chemicals inhibiting biofilm formation. To test this hypothesis, we evaluated ginger’s ability to inhibit Pseudomonas aeruginosa PA14 biofilm formation. A static biofilm assay demonstrated that biofilm development was reduced by 39–56% when ginger extract was added to the culture. In addition, various phenotypes were altered after ginger addition of PA14. Ginger extract decreased production of extracellular polymeric substances. This finding was confirmed by chemical analysis and confocal laser scanning microscopy. Furthermore, ginger extract formed noticeably less rugose colonies on agar plates containing Congo red and facilitated swarming motility on soft agar plates. The inhibition of biofilm formation and the altered phenotypes appear to be linked to a reduced level of a second messenger, bis-(3′-5′)-cyclic dimeric guanosine monophosphate. Importantly, ginger extract inhibited biofilm formation in both Gram-positive and Gram-negative bacteria. Also, surface biofilm cells formed with ginger extract detached more easily with surfactant than did those without ginger extract. Taken together, these findings provide a foundation for the possible discovery of a broad spectrum biofilm inhibitor. PMID:24086697

Colony to colorimetry in 6 h: ELISA detection of a surface-expressed Pseudomonas aeruginosa virulence factor using immobilized bacteria.

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Adawi, Azmi; Neville, Lewis F

2012-09-01

A rapid ELISA employing intact Pseudomonas aeruginosa (PA) is described that allows discrimination between strains harboring flagellin type a or b. All 52 PA strains known to harbor flagellin type b were positive in this ELISA when screened with a fully human monoclonal antibody (LST-007) targeting flagellin type b. Completion of this assay in only 6 h, from picking a single bacterial colony to a colorimetric product, could easily be adapted to a clinical laboratory setting and permit the appropriate choice of therapeutic monoclonal antibody versus its homologous flagellin target in PA-infected patients. Copyright © 2012 Elsevier Inc. All rights reserved.

Genetic improvement of Rhamnolipid Production from Pseudomonas aeruginosa

International Nuclear Information System (INIS)

Al-Gelawi, Majed Hussain; Al-Makadci, O.A.

2007-01-01

Six bacterial isolates (isolated previously) were identified and/or ensured their identification. Results showed that these isolates belong to P. aeruginosa, and all isolates were capable of producing rhamnolipid, and best ones was P. aeruginosa RB67. In order to get rhamnolipid hyper producer mutants, mutagenesis of P. aeruginosa RB 67 using UV light and MNNG were performed. Fifty colonies from each treatment (UV and MNNG) were selected and screened for their ability to produce rhamnolipid semi-quantitatively by replica plated on blood agar and CTAB-methylene blue agar. Based on the last method, twelve colonies from each treatment (UV and MNNG) were selected and used for measuring rhamnose concentration. The results showed that these mutants varied in their ability to produce rhamnolipid and some of them showed an increase in rhamnalipid production. The highest rhamnose concentration (94 ug/mL) was achieved by the mutant (MOM12). Furthermore, FTIR spectroscopy results indicated that there were no apparent qualitative differences in rhamnolipid produced from mutants. (author)

Rock-dwelling lizards exhibit less sensitivity of sprint speed to increases in substrate rugosity.

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Collins, Clint E; Self, Jessica D; Anderson, Roger A; McBrayer, Lance D

2013-06-01

Effectively moving across variable substrates is important to all terrestrial animals. The effects of substrates on lizard performance have ecological ramifications including the partitioning of habitat according to sprinting ability on different surfaces. This phenomenon is known as sprint sensitivity, or the decrease in sprint speed due to change in substrate. However, sprint sensitivity has been characterized only in arboreal Anolis lizards. Our study measured sensitivity to substrate rugosity among six lizard species that occupy rocky, sandy, and/or arboreal habitats. Lizards that use rocky habitats are less sensitive to changes in substrate rugosity, followed by arboreal lizards, and then by lizards that use sandy habitats. We infer from comparative phylogenetic analysis that forelimb, chest, and tail dimensions are important external morphological features related to sensitivity to changes in substrate rugosity. Copyright © 2013 Elsevier GmbH. All rights reserved.

Introduction of Pseudomonas aeruginosa into a Hospital via Vegetables

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Kominos, Spyros D.; Copeland, Charles E.; Grosiak, Barbara; Postic, Bosko

1972-01-01

Pseudomonas aeruginosa was isolated from tomatoes, radishes, celery, carrots, endive, cabbage, cucumbers, onions, and lettuce obtained from the kitchen of a general hospital, with tomatoes yielding both highest frequencies of isolation and highest counts. Presence of P. aeruginosa on the hands of kitchen personnel and cutting boards and knives which they used suggests acquisition of the organism through contact with these vegetables. It is estimated that a patient consuming an average portion of tomato salad might ingest as many as 5 × 103 colony-forming units of P. aeruginosa. Pyocine types of P. aeruginosa isolated from clinical specimens were frequently identical to those recovered from vegetables, thus implicating tomatoes and other vegetables as an important source and vehicle by which P. aeruginosa colonizes the intestinal tract of patients. PMID:4628795

The Cyclic AMP-Vfr Signaling Pathway in Pseudomonas aeruginosa Is Inhibited by Cyclic Di-GMP

DEFF Research Database (Denmark)

Almblad, Henrik; Harrison, Joe J; Rybtke, Morten

2015-01-01

infection give rise to rugose small colony variants (RSCVs), which are hyper-biofilm-forming mutants that commonly possess mutations that increase production of the biofilm-promoting secondary messenger cyclic di-GMP (c-di-GMP). We show that RSCVs display a decreased production of acute virulence factors...... as a direct result of elevated c-di-GMP content. Overproduction of c-di-GMP causes a decrease in the transcription of virulence factor genes that are regulated by the global virulence regulator Vfr. The low level of Vfr-dependent transcription is caused by a low level of its coactivator, cyclic AMP (c......AMP), which is decreased in response to a high level of c-di-GMP. Mutations that cause reversion of the RSCV phenotype concomitantly reactivate Vfr-cAMP signaling. Attempts to uncover the mechanism underlying the observed c-di-GMP-mediated lowering of cAMP content provided evidence that it is not caused...

An Antipersister Strategy for Treatment of Chronic Pseudomonas aeruginosa Infections.

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Koeva, Martina; Gutu, Alina D; Hebert, Wesley; Wager, Jeffrey D; Yonker, Lael M; O'Toole, George A; Ausubel, Frederick M; Moskowitz, Samuel M; Joseph-McCarthy, Diane

2017-12-01

Bacterial persisters are a quasidormant subpopulation of cells that are tolerant to antibiotic treatment. The combination of the aminoglycoside tobramycin with fumarate as an antibacterial potentiator utilizes an antipersister strategy that is aimed at reducing recurrent Pseudomonas aeruginosa infections by enhancing the killing of P. aeruginosa persisters. Stationary-phase cultures of P. aeruginosa were used to generate persister cells. A range of tobramycin concentrations was tested with a range of metabolite concentrations to determine the potentiation effect of the metabolite under a variety of conditions, including a range of pH values and in the presence of azithromycin or cystic fibrosis (CF) patient sputum. In addition, 96-well dish biofilm and colony biofilm assays were performed, and the cytotoxicity of the tobramycin-fumarate combination was determined utilizing a lactate dehydrogenase (LDH) assay. Enhanced killing of up to 6 orders of magnitude of P. aeruginosa persisters over a range of CF isolates, including mucoid and nonmucoid strains, was observed for the tobramycin-fumarate combination compared to killing with tobramycin alone. Furthermore, significant fumarate-mediated potentiation was seen in the presence of azithromycin or CF patient sputum. Fumarate also reduced the cytotoxicity of tobramycin-treated P. aeruginosa to human epithelial airway cells. Finally, in mucoid and nonmucoid CF isolates, complete eradication of P. aeruginosa biofilm was observed in the colony biofilm assay due to fumarate potentiation. These data suggest that a combination of tobramycin with fumarate as an antibacterial potentiator may be an attractive therapeutic for eliminating recurrent P. aeruginosa infections in CF patients through the eradication of bacterial persisters. Copyright © 2017 American Society for Microbiology.

Methods and measurement variance for field estimations of coral colony planar area using underwater photographs and semi-automated image segmentation.

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Neal, Benjamin P; Lin, Tsung-Han; Winter, Rivah N; Treibitz, Tali; Beijbom, Oscar; Kriegman, David; Kline, David I; Greg Mitchell, B

2015-08-01

Size and growth rates for individual colonies are some of the most essential descriptive parameters for understanding coral communities, which are currently experiencing worldwide declines in health and extent. Accurately measuring coral colony size and changes over multiple years can reveal demographic, growth, or mortality patterns often not apparent from short-term observations and can expose environmental stress responses that may take years to manifest. Describing community size structure can reveal population dynamics patterns, such as periods of failed recruitment or patterns of colony fission, which have implications for the future sustainability of these ecosystems. However, rapidly and non-invasively measuring coral colony sizes in situ remains a difficult task, as three-dimensional underwater digital reconstruction methods are currently not practical for large numbers of colonies. Two-dimensional (2D) planar area measurements from projection of underwater photographs are a practical size proxy, although this method presents operational difficulties in obtaining well-controlled photographs in the highly rugose environment of the coral reef, and requires extensive time for image processing. Here, we present and test the measurement variance for a method of making rapid planar area estimates of small to medium-sized coral colonies using a lightweight monopod image-framing system and a custom semi-automated image segmentation analysis program. This method demonstrated a coefficient of variation of 2.26% for repeated measurements in realistic ocean conditions, a level of error appropriate for rapid, inexpensive field studies of coral size structure, inferring change in colony size over time, or measuring bleaching or disease extent of large numbers of individual colonies.

Rugosity grid derived from gridded bathymetry of Kure Atoll, Hawaii, USA

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National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (5 m cell size) multibeam bathymetry, collected aboard NOAA Ship Hiialaka'i and R/V AHI, and IKONOS derived depths using the Benthic...

Grazer-induced morphological defense in Scenedesmus obliquus is affected by competition against Microcystis aeruginosa.

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Zhu, Xuexia; Wang, Jun; Lu, Yichun; Chen, Qinwen; Yang, Zhou

2015-07-30

The green alga Scenedesmus is known for its phenotypic plasticity in response to grazing risk. However, the benefits of colony formation induced by infochemicals from zooplankton should come with costs. That is, a tradeoff in benefit-to-cost ratios is likely under complex environmental conditions. In this study, we hypothesized that the coexistence of Scenedesmus and its competitors decreases the formation of anti-grazer colonies in Scenedesmus. Results demonstrated that the presence of a competitor Microcystis aeruginosa inhibited inducible defensive colony formation of Scenedesmus obliquus, and the established defensive colonies negatively affected the competitive ability of S. obliquus. The proportion of induced defensive colonies in cultures was dependent on the relative abundance of competitors. Under low competition intensity, large amount of eight-celled colonies were formed but at the cost of decreased competitive inhibition on M. aeruginosa. By contrast, defensive colony formation of S. obliquus slacked in the presence of high competition intensity to maintain a high displacement rate (competitive ability). In conclusion, S. obliquus exhibited different responses to potential grazing pressure under different intensities of competition, i.e., Scenedesmus morphological response to grazing infochemicals was affected by competition against Microcystis.

Cartographic Production for the FLaSH Map Study: Generation of Rugosity Grids, 2008

Science.gov (United States)

Robbins, Lisa L.; Knorr, Paul O.; Hansen, Mark

2010-01-01

Project Summary This series of raster data is a U.S. Geological Survey (USGS) Data Series release from the Florida Shelf Habitat Project (FLaSH). This disc contains two raster images in Environmental Systems Research Institute, Inc. (ESRI) raster grid format, jpeg image format, and Geo-referenced Tagged Image File Format (GeoTIFF). Data is also provided in non-image ASCII format. Rugosity grids at two resolutions (250 m and 1000 m) were generated for West Florida shelf waters to 250 m using a custom algorithm that follows the methods of Valentine and others (2004). The Methods portion of this document describes the specific steps used to generate the raster images. Rugosity, also referred to as roughness, ruggedness, or the surface-area ratio (Riley and others, 1999; Wilson and others, 2007), is a visual and quantitative measurement of terrain complexity, a common variable in ecological habitat studies. The rugosity of an area can affect biota by influencing habitat, providing shelter from elements, determining the quantity and type of living space, influencing the type and quantity of flora, affecting predator-prey relationships by providing cover and concealment, and, as an expression of vertical relief, can influence local environmental conditions such as temperature and moisture. In the marine environment rugosity can furthermore influence current flow rate and direction, increase the residence time of water in an area through eddying and current deflection, influence local water conditions such as chemistry, turbidity, and temperature, and influence the rate and nature of sedimentary deposition. State-of-the-art computer-mapping techniques and data-processing tools were used to develop shelf-wide raster and vector data layers. Florida Shelf Habitat (FLaSH) Mapping Project (http://coastal.er.usgs.gov/flash) endeavors to locate available data, identify data gaps, synthesize existing information, and expand our understanding of geologic processes in our dynamic

Colistin-Tobramycin Combinations Are Superior to Monotherapy Concerning the Killing of Biofilm Pseudomonas aeruginosa

DEFF Research Database (Denmark)

Herrmann, G.; Yang, Liang; Wu, H.

2010-01-01

Background. Antibiotic combination therapy might be more efficient than single antibiotics to combat Pseudomonas aeruginosa biofilms in the airways of patients with cystic fibrosis. We tested the ability of colistin sulphatetobramycin combinations and single antibiotics to kill P. aeruginosa...... biofilms. Methods. P. aeruginosa biofilms were generated in vitro and in rat lungs. In a pilot study, 5 patients with cystic fibrosis inhaled colistin and then tobramycin for 4 weeks. The changes in P. aeruginosa counts and lung function were assessed before and after therapy. Results. Antibiotic...... combination therapy significantly reduced the number of P. aeruginosa cells in P. aeruginosa biofilm models in vitro. When rats were challenged with 1 x 10(7) cfu of P. aeruginosa, which was embedded in alginate beads, mortality rates, lung pathologic findings, and bacterial colony-forming unit counts were...

How Honey Bee Colonies Survive in the Wild: Testing the Importance of Small Nests and Frequent Swarming.

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J Carter Loftus

Full Text Available The ectoparasitic mite, Varroa destructor, and the viruses that it transmits, kill the colonies of European honey bees (Apis mellifera kept by beekeepers unless the bees are treated with miticides. Nevertheless, there exist populations of wild colonies of European honey bees that are persisting without being treated with miticides. We hypothesized that the persistence of these wild colonies is due in part to their habits of nesting in small cavities and swarming frequently. We tested this hypothesis by establishing two groups of colonies living either in small hives (42 L without swarm-control treatments or in large hives (up to 168 L with swarm-control treatments. We followed the colonies for two years and compared the two groups with respect to swarming frequency, Varroa infesttion rate, disease incidence, and colony survival. Colonies in small hives swarmed more often, had lower Varroa infestation rates, had less disease, and had higher survival compared to colonies in large hives. These results indicate that the smaller nest cavities and more frequent swarming of wild colonies contribute to their persistence without mite treatments.

How Honey Bee Colonies Survive in the Wild: Testing the Importance of Small Nests and Frequent Swarming

Science.gov (United States)

Loftus, J. Carter; Smith, Michael L.; Seeley, Thomas D.

2016-01-01

The ectoparasitic mite, Varroa destructor, and the viruses that it transmits, kill the colonies of European honey bees (Apis mellifera) kept by beekeepers unless the bees are treated with miticides. Nevertheless, there exist populations of wild colonies of European honey bees that are persisting without being treated with miticides. We hypothesized that the persistence of these wild colonies is due in part to their habits of nesting in small cavities and swarming frequently. We tested this hypothesis by establishing two groups of colonies living either in small hives (42 L) without swarm-control treatments or in large hives (up to 168 L) with swarm-control treatments. We followed the colonies for two years and compared the two groups with respect to swarming frequency, Varroa infesttion rate, disease incidence, and colony survival. Colonies in small hives swarmed more often, had lower Varroa infestation rates, had less disease, and had higher survival compared to colonies in large hives. These results indicate that the smaller nest cavities and more frequent swarming of wild colonies contribute to their persistence without mite treatments. PMID:26968000

Pseudomonas aeruginosa Alters Staphylococcus aureus Sensitivity to Vancomycin in a Biofilm Model of Cystic Fibrosis Infection

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Giulia Orazi

2017-07-01

Full Text Available The airways of cystic fibrosis (CF patients have thick mucus, which fosters chronic, polymicrobial infections. Pseudomonas aeruginosa and Staphylococcus aureus are two of the most prevalent respiratory pathogens in CF patients. In this study, we tested whether P. aeruginosa influences the susceptibility of S. aureus to frontline antibiotics used to treat CF lung infections. Using our in vitro coculture model, we observed that addition of P. aeruginosa supernatants to S. aureus biofilms grown either on epithelial cells or on plastic significantly decreased the susceptibility of S. aureus to vancomycin. Mutant analyses showed that 2-n-heptyl-4-hydroxyquinoline N-oxide (HQNO, a component of the P. aeruginosa Pseudomonas quinolone signal (PQS system, protects S. aureus from the antimicrobial activity of vancomycin. Similarly, the siderophores pyoverdine and pyochelin also contribute to the ability of P. aeruginosa to protect S. aureus from vancomycin, as did growth under anoxia. Under our experimental conditions, HQNO, P. aeruginosa supernatant, and growth under anoxia decreased S. aureus growth, likely explaining why this cell wall-targeting antibiotic is less effective. P. aeruginosa supernatant did not confer additional protection to slow-growing S. aureus small colony variants. Importantly, P. aeruginosa supernatant protects S. aureus from other inhibitors of cell wall synthesis as well as protein synthesis-targeting antibiotics in an HQNO- and siderophore-dependent manner. We propose a model whereby P. aeruginosa causes S. aureus to shift to fermentative growth when these organisms are grown in coculture, leading to reduction in S. aureus growth and decreased susceptibility to antibiotics targeting cell wall and protein synthesis.

Rugosity grid derived from gridded bathymetry of Ni'ihau Island, Hawaii, USA

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (5 m cell size) multibeam bathymetry, collected aboard NOAA ship Hi'ialakai and R/V AHI using the Benthic Terrain Modeler with...

Rugosity grid derived from gridded bathymetry of French Frigate Shoals, Hawaii, USA

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (5 m cell size) multibeam bathymetry, collected aboard NOAA Ship Hiialaka'i and R/V AHI, using the Benthic Terrain Modeler with...

Effect of buprofezin and Isaria fumosorosea against rugose spiraling whitefly, 2015

Science.gov (United States)

The objective of this study was to evaluate the efficacy of selected insecticides alone or in combination against Aleurodicus rugioperculatus Martin, the rugose spiraling whitefly (RSW), a new invasive pest of ornamentals in Florida. The trial was conducted on an ornamental host, white bird of parad...

Analysis of multidrug resistant group B streptococci with reduced penicillin susceptibility forming small, less hemolytic colonies.

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Hirotsugu Banno

Full Text Available Group B streptococci (GBS; Streptococcus agalactiae are the leading cause of neonatal invasive diseases and are also important pathogens for elderly adults. Until now, nearly all GBS with reduced penicillin susceptibility (PRGBS have shown β-hemolytic activity and grow on sheep blood agar. However, we have previously reported three PRGBS clinical isolates harboring a CylK deletion that form small less hemolytic colonies. In this study, we examined the causes of small, less hemolytic colony formation in these clinical isolates. Isogenic strains were sequenced to identify the mutation related to a small colony size. We identified a 276_277insG nucleic acid insertion in the thiamin pyrophosphokinase (tpk gene, resulting in premature termination at amino acid 103 in TPK, as a candidate mutation responsible for small colony formation. The recombinant strain Δtpk, which harbored the 276_277insG insertion in the tpk gene, showed small colony formation. The recombinant strain ΔcylK, which harbored the G379T substitution in cylK, showed a reduction in hemolytic activity. The phenotypes of both recombinant strains were complemented by the expression of intact TPK or CylK, respectively. Moreover, the use of Rapid ID 32 API and VITEK MS to identify strains as GBS was evaluated clinical isolates and recombinant strains. VITEK MS, but not Rapid ID 32 API, was able to accurately identify the strains as GBS. In conclusion, we determined that mutations in tpk and cylK caused small colonies and reduced hemolytic activity, respectively, and characterized the clinical isolates in detail.

Pseudomonas biofilm matrix composition and niche biology

Science.gov (United States)

Mann, Ethan E.; Wozniak, Daniel J.

2014-01-01

Biofilms are a predominant form of growth for bacteria in the environment and in the clinic. Critical for biofilm development are adherence, proliferation, and dispersion phases. Each of these stages includes reinforcement by, or modulation of, the extracellular matrix. Pseudomonas aeruginosa has been a model organism for the study of biofilm formation. Additionally, other Pseudomonas species utilize biofilm formation during plant colonization and environmental persistence. Pseudomonads produce several biofilm matrix molecules, including polysaccharides, nucleic acids, and proteins. Accessory matrix components shown to aid biofilm formation and adaptability under varying conditions are also produced by pseudomonads. Adaptation facilitated by biofilm formation allows for selection of genetic variants with unique and distinguishable colony morphology. Examples include rugose small-colony variants and wrinkly spreaders (WS), which over produce Psl/Pel or cellulose, respectively, and mucoid bacteria that over produce alginate. The well-documented emergence of these variants suggests that pseudomonads take advantage of matrix-building subpopulations conferring specific benefits for the entire population. This review will focus on various polysaccharides as well as additional Pseudomonas biofilm matrix components. Discussions will center on structure–function relationships, regulation, and the role of individual matrix molecules in niche biology. PMID:22212072

Evolution and adaptation in Pseudomonas aeruginosa biofilms driven by mismatch repair system-deficient mutators.

Directory of Open Access Journals (Sweden)

Adela M Luján

Full Text Available Pseudomonas aeruginosa is an important opportunistic pathogen causing chronic airway infections, especially in cystic fibrosis (CF patients. The majority of the CF patients acquire P. aeruginosa during early childhood, and most of them develop chronic infections resulting in severe lung disease, which are rarely eradicated despite intensive antibiotic therapy. Current knowledge indicates that three major adaptive strategies, biofilm development, phenotypic diversification, and mutator phenotypes [driven by a defective mismatch repair system (MRS], play important roles in P. aeruginosa chronic infections, but the relationship between these strategies is still poorly understood. We have used the flow-cell biofilm model system to investigate the impact of the mutS associated mutator phenotype on development, dynamics, diversification and adaptation of P. aeruginosa biofilms. Through competition experiments we demonstrate for the first time that P. aeruginosa MRS-deficient mutators had enhanced adaptability over wild-type strains when grown in structured biofilms but not as planktonic cells. This advantage was associated with enhanced micro-colony development and increased rates of phenotypic diversification, evidenced by biofilm architecture features and by a wider range and proportion of morphotypic colony variants, respectively. Additionally, morphotypic variants generated in mutator biofilms showed increased competitiveness, providing further evidence for mutator-driven adaptive evolution in the biofilm mode of growth. This work helps to understand the basis for the specific high proportion and role of mutators in chronic infections, where P. aeruginosa develops in biofilm communities.

Rugosity 5m grid derived from gridded bathymetry of Brooks Banks, Hawaii, USA

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (5 m cell size) multibeam bathymetry, collected aboard NOAA ship Hi'ialakai and R/V AHI using the Benthic Terrain Modeler with...

Rugosity grid derived from gridded bathymetry of Pearl and Hermes Atoll, Hawaii, USA

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (5 m cell size) multibeam bathymetry, collected aboard NOAA Ship Hiialaka'i and R/V AHI, and IKONOS derived depths using the Benthic...

Population census of a large common tern colony with a small unmanned aircraft.

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Dominique Chabot

Full Text Available Small unmanned aircraft systems (UAS may be useful for conducting high-precision, low-disturbance waterbird surveys, but limited data exist on their effectiveness. We evaluated the capacity of a small UAS to census a large (>6,000 nests coastal Common tern (Sterna hirundo colony of which ground surveys are particularly disruptive and time-consuming. We compared aerial photographic tern counts to ground nest counts in 45 plots (5-m radius throughout the colony at three intervals over a nine-day period in order to identify sources of variation and establish a coefficient to estimate nest numbers from UAS surveys. We also compared a full colony ground count to full counts from two UAS surveys conducted the following day. Finally, we compared colony disturbance levels over the course of UAS flights to matched control periods. Linear regressions between aerial and ground counts in plots had very strong correlations in all three comparison periods (R2 = 0.972-0.989, P < 0.001 and regression coefficients ranged from 0.928-0.977 terns/nest. Full colony aerial counts were 93.6% and 94.0%, respectively, of the ground count. Varying visibility of terns with ground cover, weather conditions and image quality, and changing nest attendance rates throughout incubation were likely sources of variation in aerial detection rates. Optimally timed UAS surveys of Common tern colonies following our method should yield population estimates in the 93-96% range of ground counts. Although the terns were initially disturbed by the UAS flying overhead, they rapidly habituated to it. Overall, we found no evidence of sustained disturbance to the colony by the UAS. We encourage colonial waterbird researchers and managers to consider taking advantage of this burgeoning technology.

The queen is not a pacemaker in the small-colony wasps Polistes instabilis and P. dominulus

DEFF Research Database (Denmark)

Jha, Shalene; Casey-Ford, Rowan G.; Pedersen, Jes Søe

2006-01-01

How work is organized varies in social insect colonies. Some investigators have argued that the queen plays an active role in regulating worker activity in species with small, simple colonies, but that work is self-organized in species with large, complex colonies. Here, we present data that sugg...

Yeast petites and small colony variants: for everything there is a season.

Science.gov (United States)

Day, Martin

2013-01-01

The yeast petite mutant was first found in the yeast Saccharomyces cerevisiae. The colony is small because of a block in the aerobic respiratory chain pathway, which generates ATP. The petite yeasts are thus unable to grow on nonfermentable carbon sources (such as glycerol or ethanol), and form small anaerobic-sized colonies when grown in the presence of fermentable carbon sources (such as glucose). The petite phenotype results from mutations in the mitochondrial genome, loss of mitochondria, or mutations in the host cell genome. The latter mutations affect nuclear-encoded genes involved in oxidative phosphorylation and these mutants are termed neutral petites. They all produce wild-type progeny when crossed with a wild-type strain. The staphylococcal small colony variant (SCV) is a slow-growing mutant that typically exhibits the loss of many phenotypic characteristics and pathogenic traits. SCVs are mostly small, nonpigmented, and nonhaemolytic. Their small size is often due to an inability to synthesize electron transport chain components and so cannot generate ATP by oxidative phosphorylation. Evidence suggests that they are responsible for persistent and/or recurrent infections. This chapter compares the physiological and genetic basis of the petite mutants and SCVs. The review focuses principally on two representatives, the eukaryote S. cerevisiae and the prokaryote Staphylococcus aureus. There is, clearly, commonality in the physiological response. Interestingly, the similarity, based on their physiological states, has not been commented on previously. The finding of an overlapping physiological response that occurs across a taxonomic divide is novel. © 2013 Elsevier Inc. All rights reserved.

Rugosity grid (5 m) derived from gridded bathymetry of the US Territory of Guam

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National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (5 m cell size) bathymetry from four sources: Multibeam bathymetry collected by Coral Reef Ecosystem Division aboard NOAA R/V AHI,...

Triclosan-Induced Aminoglycoside-Tolerant Listeria monocytogenes Isolates Can Appear as Small-Colony Variants

DEFF Research Database (Denmark)

Kastbjerg, Vicky Gaedt; Hein-Kristensen, Line; Gram, Lone

2014-01-01

Exposure of the human food-borne pathogen Listeria monocytogenes to sublethal concentrations of triclosan can cause resistance to several aminoglycosides. Aminoglycoside-resistant isolates exhibit two colony morphologies: normal-size and pinpoint colonies. The purposes of the present study were...... to characterize the small colonies of L. monocytogenes and to determine if specific genetic changes could explain the triclosan-induced aminoglycoside resistance in both pinpoint and normal-size isolates. Isolates from the pinpoint colonies grew poorly under aerated conditions, but growth was restored by addition......I and that exposure to triclosan can cause resistance to antibiotics that enters the cell via active transport. Further studies are needed to elucidate if L. monocytogenes pinpoint isolates could have any clinical impact, e.g., in persistent infections....

Inoculation density and nutrient level determine the formation of mushroom-shaped structures in Pseudomonas aeruginosa biofilms

Science.gov (United States)

Ghanbari, Azadeh; Dehghany, Jaber; Schwebs, Timo; Müsken, Mathias; Häussler, Susanne; Meyer-Hermann, Michael

2016-09-01

Pseudomonas aeruginosa often colonises immunocompromised patients and the lungs of cystic fibrosis patients. It exhibits resistance to many antibiotics by forming biofilms, which makes it hard to eliminate. P. aeruginosa biofilms form mushroom-shaped structures under certain circumstances. Bacterial motility and the environment affect the eventual mushroom morphology. This study provides an agent-based model for the bacterial dynamics and interactions influencing bacterial biofilm shape. Cell motility in the model relies on recently published experimental data. Our simulations show colony formation by immotile cells. Motile cells escape from a single colony by nutrient chemotaxis and hence no mushroom shape develops. A high number density of non-motile colonies leads to migration of motile cells onto the top of the colonies and formation of mushroom-shaped structures. This model proposes that the formation of mushroom-shaped structures can be predicted by parameters at the time of bacteria inoculation. Depending on nutrient levels and the initial number density of stalks, mushroom-shaped structures only form in a restricted regime. This opens the possibility of early manipulation of spatial pattern formation in bacterial colonies, using environmental factors.

Inoculation density and nutrient level determine the formation of mushroom-shaped structures in Pseudomonas aeruginosa biofilms.

Science.gov (United States)

Ghanbari, Azadeh; Dehghany, Jaber; Schwebs, Timo; Müsken, Mathias; Häussler, Susanne; Meyer-Hermann, Michael

2016-09-09

Pseudomonas aeruginosa often colonises immunocompromised patients and the lungs of cystic fibrosis patients. It exhibits resistance to many antibiotics by forming biofilms, which makes it hard to eliminate. P. aeruginosa biofilms form mushroom-shaped structures under certain circumstances. Bacterial motility and the environment affect the eventual mushroom morphology. This study provides an agent-based model for the bacterial dynamics and interactions influencing bacterial biofilm shape. Cell motility in the model relies on recently published experimental data. Our simulations show colony formation by immotile cells. Motile cells escape from a single colony by nutrient chemotaxis and hence no mushroom shape develops. A high number density of non-motile colonies leads to migration of motile cells onto the top of the colonies and formation of mushroom-shaped structures. This model proposes that the formation of mushroom-shaped structures can be predicted by parameters at the time of bacteria inoculation. Depending on nutrient levels and the initial number density of stalks, mushroom-shaped structures only form in a restricted regime. This opens the possibility of early manipulation of spatial pattern formation in bacterial colonies, using environmental factors.

60 m Rugosity grid derived from gridded bathymetry of Wake Island, West Central Pacific.

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (60 m cell size) multibeam bathymetry, collected aboard NOAA ship Hi'ialakai and R/V AHI using the Benthic Terrain Modeler with...

CRED Rugosity grid derived from gridded bathymetry of Tutuila Island, American Samoa, South Pacific

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (5 m cell size) multibeam bathymetry, collected aboard NOAA Ship Hiialaka'i and R/V AHI, using the Benthic Terrain Modeler with...

Rugosity 60 m grid derived from gridded bathymetry of Rota Island, Mariana Islands, USA

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (60 m cell size) multibeam bathymetry, collected aboard NOAA Ship Hiialaka'i and R/V AHI, using the Benthic Terrain Modeler with...

Detection of Small Colony Variants Among Methicillin-Resistant Staphylococcus aureus Blood Isolates.

Science.gov (United States)

Yagci, Server; Sancak, Banu; Hascelik, Gulsen

2016-12-01

Staphylococcus aureus small colony variants (SCVs) are associated with chronic and persistent infections. Methicillin-resistant S. aureus (MRSA) SCVs cause more severe infections and mortality rates are higher in comparison with infections caused by MRSA. Our objective was to document the prevalence and phenotypical characteristics of SCVs among MRSA blood isolates. MRSA strains isolated from blood during 1999-2009 were evaluated retrospectively. Among 299 MRSA isolates, suspected colonies were inoculated onto Columbia blood agar and Schaedler agar. Columbia blood agar was incubated in normal atmosphere and Schaedler agar in 5-10% CO 2 , both at 35°C. If the small, nonpigmented, nonhemolytic colonies on Columbia blood agar were seen as normal-sized, hemolytic, and pigmented colonies on Schaedler agar, they were considered as MRSA SCVs. Six MRSA SCVs were detected. When subcultures were made, four of them reversed to phenotypically normal S. aureus, but two isolates were stable as SCV phenotype. The prevalence of SCVs among MRSA blood isolates was found as 6/299 (2%) with 2 (0.67%) stable. The detection of SCVs among MRSA blood isolates was reported from Turkey for the first time in this study. As the clinical significance of MRSA infections is well documented, evaluation of MRSA SCVs in clinical samples, especially from intensive care patients and those who have chronic and persistent infections are important to consider.

Comparison of UVB and UVC irradiation disinfection efficacies on Pseudomonas Aeruginosa (P. aeruginosa) biofilm

Science.gov (United States)

Argyraki, A.; Markvart, M.; Nielsen, Anne; Bjarnsholt, T.; Bjørndal, L.; Petersen, P. M.

2016-04-01

Disinfection routines are important in all clinical applications. The uprising problem of antibiotic resistance has driven major research efforts towards alternative disinfection approaches, involving light-based solutions. Pseudomonas aeruginosa (P. aeruginosa) is a common bacterium that can cause skin, soft tissue, lungs, kidney and urinary tract infections. Moreover, it can be found on and in medical equipment causing often cross infections in hospitals. The objective of this study was to test the efficiency, of two different light-based disinfection treatments, namely UVB and UVC irradiation, on P. aeruginosa biofilms at different growth stages. In our experiments a new type of UV light emitting diodes (LEDs) were used to deliver UV irradiation on the biofilms, in the UVB (296nm) and UVC (266nm) region. The killing rate was studied as a function of dose for 24h grown biofilms. The dose was ramped from 72J/m2 to 10000J/m2. It was shown that UVB irradiation was more effective than UVC irradiation in inactivating P. aeruginosa biofilms. No colony forming units (CFU) were observed for the UVB treated biofilms when the dose was 10000 J/m2 (CFU in control sample: 7.5 x 104). UVB irradiation at a dose of 20000J/m2 on mature biofilms (72h grown) resulted in a 3.9 log killing efficacy. The fact that the wavelength of 296nm exists in daylight and has such disinfection ability on biofilms gives new perspectives for applications within disinfection at hospitals.

Analysis of the Mechanical Behavior and Surface Rugosity of Different Dental Die Materials.

Science.gov (United States)

Niekawa, Ciro T; Kreve, Simone; A'vila, Gisseli Bertozzi; Godoy, Gilmar Gil; Eduardo Vieira da Silva, J R; Dias, Sergio Candido

2017-01-01

This work evaluated the mechanical and surface behavior of different die materials. The studied materials are polyurethane resin Exakto-Form (Bredent), Gypsum type IV, Fuji Rock EP (Gc), and Durone (Dentsply). Two metallic matrices molded in polyvinyl siloxane provided 30 cylindrical test specimens for the diametral compression test and 30 hemispherical test specimens for the surface rugosity test. The cylindrical test specimens were submitted to tests of diametral compression strength using a DL2000 universal assay machine, with a load cell of 2000 Kgf and constant speed of 1 mm/min connected to the software. Kruskal-Wallis and Dunn's nonparametric tests were used to analyze the results. The hemispheres were submitted to the surface rugosity assay using a SJ201-P rugosimeter with a sensitivity of 300 μm, speed of 0.5 mm/s, and cut-off of 0.8 mm, and the readings were taken on the convex surface of the test specimens and metallic matrix. Results were analyzed using with Fisher's least significant differences test (LSD) and Dunnett's test. Kruskal-Wallis test showed significant difference between die materials for diametral compression strength ( P = 0.002). Dunn's test showed significantly higher values for modified polyurethane resin (Exakto-Form). The gypsum type IV, which did not significantly differ regarding diametral compression strength, showed 34.0% (Durone) and 42.7% (Fuji Rock) lower values in comparison to Exakto-Form. Within the parameters adopted in this study, it is possible to conclude that Exakto-Form polyurethane resin showed higher resistance to compression and was closer to the metallic matrix rugosity, and, along with the gypsum type IV Durone, showed better reproducibility of details relative to the Fuji Rock.

Small-cell comb does not control Varroa mites in colonies of honeybees of European origin

OpenAIRE

Seeley , Thomas; Griffin , Sean

2011-01-01

International audience; We tested the idea that Varroa destructor can be controlled in colonies of the European subspecies of Apis mellifera by providing them with combs built of small cells, in which immature mites might have difficulty developing for lack of space. We established seven pairs of equal-size colonies that started out equally infested with mites. In each pair, one hive contained only standard-cell (5.4 mm) comb, and the other contained only small-cell (4.8 mm) comb. We measured...

Rugosity grid derived from gridded bathymetry of Howland Island, Pacific Remote Island Areas, Central Pacific

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (40 m cell size) multibeam bathymetry, collected aboard R/V AHI and NOAA ship Hi'ialakai. Cell values reflect the (surface area) /...

Identification of small molecule inhibitors of Pseudomonas aeruginosa exoenzyme S using a yeast phenotypic screen.

Directory of Open Access Journals (Sweden)

Anthony Arnoldo

2008-02-01

Full Text Available Pseudomonas aeruginosa is an opportunistic human pathogen that is a key factor in the mortality of cystic fibrosis patients, and infection represents an increased threat for human health worldwide. Because resistance of Pseudomonas aeruginosa to antibiotics is increasing, new inhibitors of pharmacologically validated targets of this bacterium are needed. Here we demonstrate that a cell-based yeast phenotypic assay, combined with a large-scale inhibitor screen, identified small molecule inhibitors that can suppress the toxicity caused by heterologous expression of selected Pseudomonas aeruginosa ORFs. We identified the first small molecule inhibitor of Exoenzyme S (ExoS, a toxin involved in Type III secretion. We show that this inhibitor, exosin, modulates ExoS ADP-ribosyltransferase activity in vitro, suggesting the inhibition is direct. Moreover, exosin and two of its analogues display a significant protective effect against Pseudomonas infection in vivo. Furthermore, because the assay was performed in yeast, we were able to demonstrate that several yeast homologues of the known human ExoS targets are likely ADP-ribosylated by the toxin. For example, using an in vitro enzymatic assay, we demonstrate that yeast Ras2p is directly modified by ExoS. Lastly, by surveying a collection of yeast deletion mutants, we identified Bmh1p, a yeast homologue of the human FAS, as an ExoS cofactor, revealing that portions of the bacterial toxin mode of action are conserved from yeast to human. Taken together, our integrated cell-based, chemical-genetic approach demonstrates that such screens can augment traditional drug screening approaches and facilitate the discovery of new compounds against a broad range of human pathogens.

Bacteria of the Burkholderia cepacia complex are cyanogenic under biofilm and colonial growth conditions

Directory of Open Access Journals (Sweden)

Hoshino Saiko

2008-06-01

Full Text Available Abstract Background The Burkholderia cepacia complex (Bcc is a collection of nine genotypically distinct but phenotypically similar species. They show wide ecological diversity and include species that are used for promoting plant growth and bio-control as well species that are opportunistic pathogens of vulnerable patients. Over recent years the Bcc have emerged as problematic pathogens of the CF lung. Pseudomonas aeruginosa is another important CF pathogen. It is able to synthesise hydrogen cyanide (HCN, a potent inhibitor of cellular respiration. We have recently shown that HCN production by P. aeruginosa may have a role in CF pathogenesis. This paper describes an investigation of the ability of bacteria of the Bcc to make HCN. Results The genome of Burkholderia cenocepacia has 3 putative HCN synthase encoding (hcnABC gene clusters. B. cenocepacia and all 9 species of the Bcc complex tested were able to make cyanide at comparable levels to P. aeruginosa, but only when grown surface attached as colonies or during biofilm growth on glass beads. In contrast to P. aeruginosa and other cyanogenic bacteria, cyanide was not detected during planktonic growth of Bcc strains. Conclusion All species in the Bcc are cyanogenic when grown as surface attached colonies or as biofilms.

Stratified growth in Pseudomonas aeruginosa biofilms

DEFF Research Database (Denmark)

Werner, E.; Roe, F.; Bugnicourt, A.

2004-01-01

In this study, stratified patterns of protein synthesis and growth were demonstrated in Pseudomonas aeruginosa biofilms. Spatial patterns of protein synthetic activity inside biofilms were characterized by the use of two green fluorescent protein (GFP) reporter gene constructs. One construct...... synthesis was restricted to a narrow band in the part of the biofilm adjacent to the source of oxygen. The zone of active GFP expression was approximately 60 Am wide in colony biofilms and 30 Am wide in flow cell biofilms. The region of the biofilm in which cells were capable of elongation was mapped...... by treating colony biofilms with carbenicillin, which blocks cell division, and then measuring individual cell lengths by transmission electron microscopy. Cell elongation was localized at the air interface of the biofilm. The heterogeneous anabolic patterns measured inside these biofilms were likely a result...

Enterococcus faecium small colony variant endocarditis in an immunocompetent patient

Directory of Open Access Journals (Sweden)

S. Hernández Egido

2016-01-01

Full Text Available Small colony variants (SCV are slow-growing subpopulations of bacteria usually associated with auxotrophism, causing persistent or recurrent infections. Enterococcus faecalis SCV have been seldom described, and only one case of Enterococcus faecium SCV has been reported, associated with sepsis in a leukaemia patient. Here we report the first case described of bacteraemia and endocarditis by SCV E. faecium in an immunocompetent patient.

Rugosity grid (5 m) derived from gridded bathymetry of Saipan Island, Commonwealth of the Northern Marianas

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (5 m cell size) bathymetry from two sources: Multibeam bathymetry collected by Coral Reef Ecosystem Division aboard NOAA R/V AHI,...

Identification and discrimination of Pseudomonas aeruginosa bacteria grown in blood and bile by laser-induced breakdown spectroscopy

International Nuclear Information System (INIS)

Rehse, Steven J.; Diedrich, Jonathan; Palchaudhuri, Sunil

2007-01-01

Pseudomonas aeruginosa bacteria colonies have been analyzed by laser-induced breakdown spectroscopy using nanosecond laser pulses. LIBS spectra were obtained after transferring the bacteria from a nutrient-rich culture medium to a nutrient-free agar plate for laser ablation. To study the dependence of the LIBS spectrum on growth and environmental conditions, colonies were cultured on three different nutrient media: a trypticase soy agar (TSA) plate, a blood agar plate, and a medium chosen deliberately to induce bacteria membrane changes, a MacConkey agar plate containing bile salts. Nineteen atomic and ionic emission lines in the LIBS spectrum, which was dominated by inorganic elements such as calcium, magnesium and sodium, were used to identify and classify the bacteria. A discriminant function analysis was used to discriminate between the P. aeruginosa bacteria and two strains of E. coli: a non-pathogenic environmental strain and the pathogenic strain enterohemorrhagic E. coli 0157:H7 (EHEC). Nearly identical spectra were obtained from P. aeruginosa grown on the TSA plate and the blood agar plate, while the bacteria grown on the MacConkey plate exhibited easily distinguishable differences from the other two. All P. aeruginosa samples, independent of initial growth conditions, were readily discriminated from the two E. coli strains

Rugosity grid derived from gridded bathymetry of of Baker Island, Pacific Remote Island Areas, Central Pacific.

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (20 m cell size) multibeam bathymetry, collected aboard R/V AHI and NOAA ship Hi'ialakai. Cell values reflect the (surface area) /...

Rugosity grid derived from gridded bathymetry of of Johnston Island, Pacific Remote Island Areas, Central Pacific.

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (20 m cell size) multibeam bathymetry, collected aboard R/V AHI and NOAA ship Hi'ialakai. Cell values reflect the (surface area) /...

Increased concentration of Pseudomonas aeruginosa and Staphylococcus sp. in small animals exposed to aerospace environments

Science.gov (United States)

Guthrie, R. K.

1976-01-01

The effects of increased concentrations of PSEUDOMONAS AERUGINOSA AND STAPHYLOCOCCUS in the total bacterial flora of small animals exposed to simulated spacecraft environments were evaluated. Tests to detect changes in infectivity, effects of antibiotic treatments, immune responses to bacterial antigens, and effectiveness of immune responses in the experimental environment were conducted. The most significant results appear to be the differences in immune responses at simulated altitudes and the production of infection in the presence of a specific antibody.

[Immunization with Bifidobacterium bifidum-vectored OprI vaccine of Pseudomonas aeruginosa enhances inhibitory effect on P. aeruginosa in mice].

Science.gov (United States)

Liu, Xiao; Li, Wengui

2017-08-01

Objective To study the pulmonary bacterial loads, splenocyte proliferation, distributions of T cell subsets and cell apoptosis in mice immunized with Bifidobacterium bifidum-vectored OprI (Bb-OprI) vaccine of Pseudomonas aeruginosa and challenged with P. aeruginosa PA01 strain. Methods BALB/c mice were immunized with 5×10 9 CFUs of vaccine by intragastric administration, 3 times a week for 3 weeks, and challenged intranasally with 5×10 6 CFUs of PA01 strain at the fourth week after the first immunization. At the second week after the challenge, all mice were sacrificed to separate their lungs and spleens, and the pulmonary bacterial loads were counted. The proliferation of the splenocytes was determined by MTT assay. The splenic CD4 + , CD8 + T cell subsets and the apoptotic rate of splenocytes were detected by flow cytometry. Results The number of pulmonary bacterial colonies in the mice immunized with the vaccine and challenged with PA01 strain decreased, while the proliferation of splenocytes and the proportion of CD4 + T cells markedly increased, and the apoptosis of splenocytes was notably reduced. Conclusion The intragastric vaccination of recombinant Bb-OprI vaccine can increase the proportion of CD4 + T cells and enhance the inhibitory effect on P. aeruginosa.

Arthropod consumption by small mammals on prairie dog colonies and adjacent ungrazed mixed grass prairie in western South Dakota

Science.gov (United States)

W. Agnew; Daniel W. Uresk; R. M. Hansen

1988-01-01

The percentage of arthropods and plants in the diets of seven small rodents captured on prairie dog colonies and adjacent mixed grasslands were estimated by microhistological techniques. Arthropod composition over the two year study averaged 51% and 37% on prairie dog colonies and mixed grasslands, respectively. Composition of arthropods on prairie dog colonies was...

Origin and characteristics of Pseudomonas aeruginosa PAO1 clones surviving after the induction of transposable prophages

Energy Technology Data Exchange (ETDEWEB)

Krylov, V.N.; Solov`era, T.I.; Burkal`tseva, M.V. [State Research Institute of Genetics and Selection of Industrial Microorganisms, Moscow (Russian Federation)] [and others

1995-08-01

Various mutations cancelling the lethal effect of phage lytic development and simultaneous phenotypic modifications were found in rare clones surviving after incubation at 42{degrees}C of Pseudomonas aeruginosa (D3112 cts15), lysogenic for thermoinducible mutant cts15 of the transposable prophage (TP) D3112. All mutations arose prior to thermal induction. Temperature induction of other bacteriophages (nontransposable) did not lead to selection of bacterial morphological mutants. Therefore, it was concluded that mutagenesis occurred upon the partial (reversible) TP derepression accompanied by coupled replication-transposition of TP, the latter being the direct cause of the mutator effect. Isolation of the P. aeruginosa PAO1 mutant R10 (this mutant is resistant to infection with TP at 42{degrees}C) allowed the proper selection and examination of numerous survivors. Comparison of their types derived from lysogens with different prophage location indicated that the number of secondary sites where TP integration is possible without the loss of cell viability is limited. Several transposition events occurred in the history of some survivors (during a repeated or single derepression event). Type D clones, which produce small colonies, are of special interest, because mechanisms underlying the survival of such clones are extremely diverse, and their phenotypes indicate the possibility of stable chromosomal rearrangements in the genome of P. aeruginosa. 16 refs., 2 figs., 2 tabs.

Effect of Negative Pressure on Proliferation, Virulence Factor Secretion, Biofilm Formation, and Virulence-Regulated Gene Expression of Pseudomonas aeruginosa In Vitro

Directory of Open Access Journals (Sweden)

Guo-Qi Wang

2016-01-01

Full Text Available Objective. To investigate the effect of negative pressure conditions induced by NPWT on P. aeruginosa. Methods. P. aeruginosa was cultured in a Luria–Bertani medium at negative pressure of −125 mmHg for 24 h in the experimental group and at atmospheric pressure in the control group. The diameters of the colonies of P. aeruginosa were measured after 24 h. ELISA kit, orcinol method, and elastin-Congo red assay were used to quantify the virulence factors. Biofilm formation was observed by staining with Alexa Fluor® 647 conjugate of concanavalin A (Con A. Virulence-regulated genes were determined by quantitative RT-PCR. Results. As compared with the control group, growth of P. aeruginosa was inhibited by negative pressure. The colony size under negative pressure was significantly smaller in the experimental group than that in the controls (p<0.01. Besides, reductions in the total amount of virulence factors were observed in the negative pressure group, including exotoxin A, rhamnolipid, and elastase. RT-PCR results revealed a significant inhibition in the expression level of virulence-regulated genes. Conclusion. Negative pressure could significantly inhibit the growth of P. aeruginosa. It led to a decrease in the virulence factor secretion, biofilm formation, and a reduction in the expression level of virulence-regulated genes.

Rugosity grid derived from gridded bathymetry of Ta'u Island of the Manu'a Island group, American Samoa

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (5 m cell size) multibeam bathymetry, collected aboard R/V AHI, and bathymetry derived from multispectral IKONOS satellite imagery...

Rugosity grid derived from gridded bathymetry Ofu and Olosega Islands of the Manu'a Island group, American Samoa

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (5 m cell size) multibeam bathymetry, collected aboard R/V AHI, and bathymetry derived from multispectral IKONOS satellite imagery...

Identification of point mutations in clinical Staphylococcus aureus strains that produce small-colony variants auxotrophic for menadione.

Science.gov (United States)

Dean, Melissa A; Olsen, Randall J; Long, S Wesley; Rosato, Adriana E; Musser, James M

2014-04-01

Staphylococcus aureus small-colony variants (SCVs) are implicated in chronic and relapsing infections that are difficult to diagnose and treat. Despite many years of study, the underlying molecular mechanisms and virulence effect of the small-colony phenotype remain incompletely understood. We sequenced the genomes of five S. aureus SCV strains recovered from human patients and discovered previously unidentified nonsynonymous point mutations in three genes encoding proteins in the menadione biosynthesis pathway. Analysis of genetic revertants and complementation with wild-type alleles confirmed that these mutations caused the SCV phenotype and decreased virulence for mice.

Phenotypic shift in Pseudomonas aeruginosa populations from cystic fibrosis lungs after 2-week antipseudomonal treatment

DEFF Research Database (Denmark)

Fernandez-Barat, Laia; Ciofu, Oana; Kragh, Kasper N.

2017-01-01

) colony-forming units (CFU/mL), b) frequency of mucoids and non-mucoids, c) resistance pattern to anti-pseudomonal drugs, d) hypermutability, e) transcriptomic profiles, and f) presence of biofilms. Results We collected 23 sputum samples (12 before antibiotic treatment and 11 after) and 77 P. aeruginosa...

Tracking down antibiotic-resistant Pseudomonas aeruginosa isolates in a wastewater network.

Directory of Open Access Journals (Sweden)

Céline Slekovec

Full Text Available The Pseudomonas aeruginosa-containing wastewater released by hospitals is treated by wastewater treatment plants (WWTPs, generating sludge, which is used as a fertilizer, and effluent, which is discharged into rivers. We evaluated the risk of dissemination of antibiotic-resistant P. aeruginosa (AR-PA from the hospital to the environment via the wastewater network. Over a 10-week period, we sampled weekly 11 points (hospital and urban wastewater, untreated and treated water, sludge of the wastewater network and the river upstream and downstream of the WWTP of a city in eastern France. We quantified the P. aeruginosa load by colony counting. We determined the susceptibility to 16 antibiotics of 225 isolates, which we sorted into three categories (wild-type, antibiotic-resistant and multidrug-resistant. Extended-spectrum β-lactamases (ESBLs and metallo-β-lactamases (MBLs were identified by gene sequencing. All non-wild-type isolates (n = 56 and a similar number of wild-type isolates (n = 54 were genotyped by pulsed-field gel electrophoresis and multilocus sequence typing. Almost all the samples (105/110, 95.5% contained P. aeruginosa, with high loads in hospital wastewater and sludge (≥3×10(6 CFU/l or/kg. Most of the multidrug-resistant isolates belonged to ST235, CC111 and ST395. They were found in hospital wastewater and some produced ESBLs such as PER-1 and MBLs such as IMP-29. The WWTP greatly reduced P. aeruginosa counts in effluent, but the P. aeruginosa load in the river was nonetheless higher downstream than upstream from the WWTP. We conclude that the antibiotic-resistant P. aeruginosa released by hospitals is found in the water downstream from the WWTP and in sludge, constituting a potential risk of environmental contamination.

LIDAR optical rugosity of coral reefs in Biscayne National Park, Florida

Science.gov (United States)

Brock, J.C.; Wright, C.W.; Clayton, T.D.; Nayegandhi, A.

2004-01-01

The NASA Experimental Advanced Airborne Research Lidar (EAARL), a temporal waveform-resolving, airborne, green wavelength LIDAR (light detection and ranging), is designed to measure the submeter-scale topography of shallow reef substrates. Topographic variability is a prime component of habitat complexity, an ecological factor that both expresses and controls the abundance and distribution of many reef organisms. Following the acquisition of EAARL coverage over both mid-platform patch reefs and shelf-margin bank reefs within Biscayne National Park in August 2002, EAARL-based optical indices of topographic variability were evaluated at 15 patch reef and bank reef sites. Several sites were selected to match reefs previously evaluated in situ along underwater video and belt transects. The analysis used large populations of submarine topographic transects derived from the examination of closely spaced laser spot reflections along LIDAR raster scans. At all 15 sites, each LIDAR transect was evaluated separately to determine optical rugosity (Rotran), and the average elevation difference between adjacent points (Av(??E ap)). Further, the whole-site mean and maximum values of Ro tran and Av(??Eap) for the entire population of transects at each analysis site, along with their standard deviations, were calculated. This study revealed that the greater habitat complexity of inshore patch reefs versus outer bank reefs results in relative differences in topographic complexity that can be discerned in the laser returns. Accordingly, LIDAR sensing of optical rugosity is proposed as a complementary new technique for the rapid assessment of shallow coral reefs. ?? Springer-Verlag 2004.

Two genetic loci produce distinct carbohydrate-rich structural components of the Pseudomonas aeruginosa biofilm matrix.

Science.gov (United States)

Friedman, Lisa; Kolter, Roberto

2004-07-01

Pseudomonas aeruginosa forms biofilms, which are cellular aggregates encased in an extracellular matrix. Molecular genetics studies of three common autoaggregative phenotypes, namely wrinkled colonies, pellicles, and solid-surface-associated biofilms, led to the identification of two loci, pel and psl, that are involved in the production of carbohydrate-rich components of the biofilm matrix. The pel gene cluster is involved in the production of a glucose-rich matrix material in P. aeruginosa strain PA14 (L. Friedman and R. Kolter, Mol. Microbiol. 51:675-690, 2004). Here we investigate the role of the pel gene cluster in P. aeruginosa strain ZK2870 and identify a second genetic locus, termed psl, involved in the production of a mannose-rich matrix material. The 11 predicted protein products of the psl genes are homologous to proteins involved in carbohydrate processing. P. aeruginosa is thus able to produce two distinct carbohydrate-rich matrix materials. Either carbohydrate-rich matrix component appears to be sufficient for mature biofilm formation, and at least one of them is required for mature biofilm formation in P. aeruginosa strains PA14 and ZK2870. Copyright 2004 American Society for Microbiology

Evidence of MexT-independent overexpression of MexEF-OprN multidrug efflux pump of Pseudomonas aeruginosa in presence of metabolic stress.

Directory of Open Access Journals (Sweden)

Ayush Kumar

Full Text Available The Pseudomonas aeruginosa MexEF-OprN efflux pump confers resistance to clinically significant antibiotics. Regulation of mexEF-oprN operon expression is multifaceted with the MexT activator being one of the most prominent regulatory proteins.We have exploited the impaired metabolic fitness of a P. aeruginosa mutant strain lacking several efflux pump of the resistance nodulation cell division superfamily and the TolC homolog OpmH, and isolated derivatives (large colony variants that regained fitness by incubation on nutrient-rich medium in the absence of antibiotics. Although the mexEF-oprN operon is uninducible in this mutant due to a 8-bp mexT insertion present in some P. aeruginosa PAO1 strains, the large colony variants expressed high levels of MexEF-OprN. Unlike large colony variants obtained after plating on antibiotic containing medium which expressed mexEF-oprN in a MexT-dependent fashion as evidenced by clean excision of the 8-bp insertion from mexT, mexEF-oprN expression was MexT-independent in the large colony variants obtained by plating on LB alone since the mexT gene remained inactivated. A search for possible regulators of mexEF-oprN expression using transposon mutagenesis and genomic library expression approaches yielded several candidates but proved inconclusive.Our results show that antibiotic and metabolic stress lead to up-regulation of MexEF-OprN expression via different mechanisms and that MexEF-OprN does not only extrude antimicrobials but rather serves other important metabolic functions.

Rugosity 10 m grid derived from gridded bathymetry of Alamagan Island, Commonwealth of the Northern Mariana Islands (CNMI), USA

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (10 m cell size) multibeam bathymetry, collected aboard NOAA Ship Hi'ialakai and R/V AHI, using the Benthic Terrain Modeler with...

Rugosity 10 m grid derived from gridded bathymetry of Pagan Island, Commonwealth of the Northern Mariana Islands (CNMI), USA

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (10 m cell size) multibeam bathymetry, collected aboard NOAA Ship Hiialaka'i and R/V AHI, using the Benthic Terrain Modeler with...

Rugosity 10 m grid derived from gridded bathymetry of Agrihan Island, Commonwealth of the Northern Mariana Islands (CNMI), USA

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (10 m cell size) multibeam bathymetry, collected aboard NOAA Ship Hiialaka'i and R/V AHI, using the Benthic Terrain Modeler with...

Rugosity 10 m grid derived from gridded bathymetry of Maug Island, Commonwealth of the Northern Mariana Islands (CNMI), USA

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (10 m cell size) multibeam bathymetry, collected aboard NOAA Ship Hiialaka'i and R/V AHI, using the Benthic Terrain Modeler with...

Rugosity 10 m grid derived from gridded bathymetry of Asuncion Island, Commonwealth of the Northern Mariana Islands (CNMI), USA

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (10 m cell size) multibeam bathymetry collected aboard NOAA Ship Hiialaka'i and R/V AHI, using the Benthic Terrain Modeler with...

Rugosity 10 m grid derived from gridded bathymetry of Guguan Island, Commonwealth of the Northern Mariana Islands (CNMI), USA

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (5 m cell size) multibeam bathymetry, collected aboard NOAA Ship Hiialaka'i and R/V AHI, using the Benthic Terrain Modeler with...

Spatial variation in keystone effects: Small mammal diversity associated with black-tailed prairie dog colonies

Science.gov (United States)

Cully, J.F.; Collinge, S.K.; Van Nimwegen, R. E.; Ray, C.; Johnson, W.C.; Thiagarajan, Bala; Conlin, D.B.; Holmes, B.E.

2010-01-01

Species with extensive geographic ranges may interact with different species assemblages at distant locations, with the result that the nature of the interactions may vary spatially. Black-tailed prairie dogs Cynomys ludovicianus occur from Canada to Mexico in grasslands of the western Great Plains of North America. Black-tailed prairie dogs alter vegetation and dig extensive burrow systems that alter grassland habitats for plants and other animal species. These alterations of habitat justify the descriptor " ecological engineer," and the resulting changes in species composition have earned them status as a keystone species. We examined the impact of black-tailed prairie dogs on small mammal assemblages by trapping at on- and off-colony locations at eight study areas across the species' geographic range. We posed 2 nested hypotheses: 1) prairie dogs function as a keystone species for other rodent species; and 2) the keystone role varies spatially. Assuming that it does, we asked what are the sources of the variation? Black-tailed prairie dogs consistently functioned as a keystone species in that there were strong statistically significant differences in community composition on versus off prairie dog colonies across the species range in prairie grassland. Small mammal species composition varied along both latitudinal and longitudinal gradients, and species richness varied from 4 to 11. Assemblages closer together were more similar; such correlations approximately doubled when including only on- or off-colony grids. Black-tailed prairie dogs had a significant effect on associated rodent assemblages that varied regionally, dependent upon the composition of the local rodent species pool. Over the range of the black-tailed prairie dog, on-colony rodent richness and evenness were less variable, and species composition was more consistent than off-colony assemblages. ?? 2010 The Authors.

Carbon and nitrogen isotopic analysis of coral-associated nitrogen in rugose corals of the Middle Devonian, implications for paleoecology and paleoceanography.

Science.gov (United States)

Hickey, A. N.; Junium, C. K.; Uveges, B. T.; Ivany, L. C.; Martindale, R. C.

2017-12-01

The Middle Devonian Appalachian Basin of Central New York hosts an extraordinary diversity of well-studied fossil invertebrates within the shallow marine sequences of the Givetian Age, Hamilton Group. Of particular interest are a series of aerially expansive coral beds with diverse assemblages of rugose corals. These well-preserved specimens provide an excellent opportunity to test the feasibility of δ15N and δ13C analyses in rugose corals in an effort to resolve outstanding issues regarding their paleoecology and ontogeny as well environmental dynamics within the Devonian Appalachian Basin. Here we present carbon and nitrogen isotope analyses of the rugose corals Heliophyllum and Siphonophrentis from the Joshua Coral Bed. Corals were cleaned of the host calcareous shale and sonicated sequentially in deionized water and methanol, and then oxidatively cleaned. Cleaned corals were sectioned into 0.5cm billets to obtain enough residual organic material for analysis. The organic content of the corals is low, but nanoEA allows for serial sampling of 5-10 samples per coral. Coral sections were decarbonated and the residual organic material is filtered and dried prior to analysis. Coral organic matter is analyzed in triplicate using nanoEA, which is a cryo-trapping, capillary focusing technique for δ15N and δ13C. The δ15N of organic matter extracted from rugose corals is, on average, enriched by 2-4‰ relative to the bulk nitrogen in the host rock. As well, the δ13C of organic carbon from the corals is 13C-enriched relative to the bulk rock, but to a lesser degree (no more than 1.5‰). Assuming that the bulk rock carbon and nitrogen are largely representative of the long-term primary production background, the modest enrichment is consistent with a trophic effect, and that rugose corals are likely planktivores. In an individual coral, δ15N ranges by 3-4‰ over its length, and when adjusted for trophic enrichment varies around the average δ15N of bulk

Evolution and Adaptation in Pseudomonas aeruginosa Biofilms Driven by Mismatch Repair System-Deficient Mutators

DEFF Research Database (Denmark)

Luján, Adela M.; Maciá, María D.; Yang, Liang

2011-01-01

, which are rarely eradicated despite intensive antibiotic therapy. Current knowledge indicates that three major adaptive strategies, biofilm development, phenotypic diversification, and mutator phenotypes [driven by a defective mismatch repair system (MRS)], play important roles in P. aeruginosa chronic...... infections, but the relationship between these strategies is still poorly understood. We have used the flow-cell biofilm model system to investigate the impact of the mutS associated mutator phenotype on development, dynamics, diversification and adaptation of P. aeruginosa biofilms. Through competition...... diversification, evidenced by biofilm architecture features and by a wider range and proportion of morphotypic colony variants, respectively. Additionally, morphotypic variants generated in mutator biofilms showed increased competitiveness, providing further evidence for mutator-driven adaptive evolution...

The entomopathogenic fungus Isaria fumosorosea and its compatibility with buprofezin: effects on the rugose spiraling whitefly Aleurodicus rugioperculatus

Science.gov (United States)

The gumbo limbo or rugose spiraling whitefly is a new invasive pest of palms, woody ornamentals, and fruits in Florida. The pathogenicity of a naturally occurring entomopathogenic fungus, Isaria fumosorosea (PFR 97) is well known for its activity against commonly found whiteflies species in the regi...

Inclusion bodies induced by bean rugose mosaic virus seen under light microscopy

Directory of Open Access Journals (Sweden)

Carmen Rivera

2000-12-01

Full Text Available Two types of inclusion bodies were consistently observed under light microscopy in bean (Phaseolus vulgaris leaf tissue infected with bean rugose mosaic virus (BRMV, a species of the genus Comovirus, family Comoviridae. One type consisted of vacuolated inclusions found mainly in the cytoplasm of epidermal cells. The other type consisted of abundant crystalloid inclusions of different sizes and shapes found consistently in glandular hairs, guard cells, phloem tissue, xylem elements and occasionally in epidermal and mesophyll tissues. The two types of inclusion bodies stained with Azure A and Luxol Brilliant Green Bl-Calcomine Orange 2RS (O-G, and were similar to those seen to be caused by other species of comoviruses.Se observaron dos tipos de inclusiones virales, mediante microscopia de luz, en hojas de plantas de frijol (Phaseolus vulgaris previamente infectadas con el virus del mosaico rugoso del frijol ("bean rugose mosaic comovirus", BRMV, especie del género Comovirus, familia Comoviridae. Se hallaron inclusiones vesiculadas, principalmente en el citoplasma de células de la epidermis, y abundantes inclusiones cristalinas de diferentes formas y tamaños siempre en células guarda, tricomas glandulares, floema, elementos del xilema y ocasionalmente en células epidérmicas y del mesófilo. Ambos tipos de inclusiones tiñeron con Azure A y con la tinción, verde naranja (Luxol Brilliant Green BL-Calcomine Orange 2 RS conocida como OG, y son similares a las inclusiones inducidas por otras especies del género Comovirus.

Comparative genome and transcriptome analysis reveals distinctive surface characteristics and unique physiological potentials of Pseudomonas aeruginosa ATCC 27853

KAUST Repository

Cao, Huiluo

2017-06-12

Pseudomonas aeruginosa ATCC 27853 was isolated from a hospital blood specimen in 1971 and has been widely used as a model strain to survey antibiotics susceptibilities, biofilm development, and metabolic activities of Pseudomonas spp.. Although four draft genomes of P. aeruginosa ATCC 27853 have been sequenced, the complete genome of this strain is still lacking, hindering a comprehensive understanding of its physiology and functional genome.Here we sequenced and assembled the complete genome of P. aeruginosa ATCC 27853 using the Pacific Biosciences SMRT (PacBio) technology and Illumina sequencing platform. We found that accessory genes of ATCC 27853 including prophages and genomic islands (GIs) mainly contribute to the difference between P. aeruginosa ATCC 27853 and other P. aeruginosa strains. Seven prophages were identified within the genome of P. aeruginosa ATCC 27853. Of the predicted 25 GIs, three contain genes that encode monoxoygenases, dioxygenases and hydrolases that could be involved in the metabolism of aromatic compounds. Surveying virulence-related genes revealed that a series of genes that encode the B-band O-antigen of LPS are lacking in ATCC 27853. Distinctive SNPs in genes of cellular adhesion proteins such as type IV pili and flagella biosynthesis were also observed in this strain. Colony morphology analysis confirmed an enhanced biofilm formation capability of ATCC 27853 on solid agar surface compared to Pseudomonas aeruginosa PAO1. We then performed transcriptome analysis of ATCC 27853 and PAO1 using RNA-seq and compared the expression of orthologous genes to understand the functional genome and the genomic details underlying the distinctive colony morphogenesis. These analyses revealed an increased expression of genes involved in cellular adhesion and biofilm maturation such as type IV pili, exopolysaccharide and electron transport chain components in ATCC 27853 compared with PAO1. In addition, distinctive expression profiles of the

Genome-wide identification of novel small RNAs in Pseudomonas aeruginosa

DEFF Research Database (Denmark)

Gómez Lozano, María

and RNA sequencing (RNAseq) technologies. The latter approach, in particular, has revolutionized sRNA discovery by enabling interrogation of the transcriptome at unprecedented depths. The size and complexity of the P. aeruginosa genome suggests that it encodes many hitherto undetected sRNAs. In this study...

Demonstration of Mycoplasma capricolum subsp capripneumoniae and Mycoplasma mycoides subsp mycoides, small colony type in outbreaks of caprine pleuropneumonia in eastern Tanzania

DEFF Research Database (Denmark)

Kusiluka, L.J.M.; Semuguruka, W.D.; Kazwala, R.R.

2000-01-01

by different degrees of vasculitis, and fibrinocellular exudation into the alveolar septae and lumina, and into interlobular septae and pleura. Mycoplasma capricolum subsp. capripneumoniae, Mycoplasma mycoides subsp. mycoides, Small Colony type Mycoplasma ovipneumoniae and Mycoplasma arginini were isolated...... from some of the examined goats including a case with a sequestrum which yielded Mycoplasma mycoides subsp. mycoides, Small Colony type. This work reports the first description of an outbreak of caprine pleuropneumonia in Tanzania in which M. capripneumoniae and M. mycoides subsp. mycoides, Small...

Rugosity grid derived from gridded bathymetry of Thirty-Five Fathom Bank and Thirty-Seven Fathom Bank, Commonwealth of the Northern Marianas.

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (5 m cell size) multibeam bathymetry, aboard NOAA Ship Oscar Elton Sette. Cell values reflect the (surface area) / (planimetric...

Effects of gamma Rays Irradiation on resistance of Pseudomonas aeruginosa in various condition

International Nuclear Information System (INIS)

Nikham

2002-01-01

The investigation of gamma tays 60Co irradiation effect on resistance of bacteri P.aeruginosa has been done.The objective of the research was to know the D10 value of bacteria P.aeruginosa. By using of distilled water,talc and peanut powder as carrier in dry,wet,O 2 and N 2 condition the bacteria of P.aeruginosa were irradiated on gamma rays of 6 0Co with dose of O to 2.5 kGy,and with dose rate of 5 and 10 kGy/h.After irradiation the bacteria of P. aeruginosa were cultured in media of the Tryptone Soya Agar and incubatedat temperature of 32±2 o C for 3 days. The survival colonies were calculated,and the data were used to make the curve and to determine the D10 value. The results of the experiments showed that D10 value of irradiated bacteria of P.aeruginosain the disitilled water,talc and peanut powder as carrier were not high significant.Nevertheless the D10 value of the irradiated at dose rate 10kGy/h show more higher tendency than at dose rate 5kGy/h. The D10 value of irradiated bacteria in the N2 condition was higher,if compared with in the O2 condition

Autoradiography of the bacterial colony. Application to the effects of polymyxin on the colony of Ps. aeruginosa

International Nuclear Information System (INIS)

Reyrolle, Jean; Letellier, Francois; Kauffmann, Jacques

1975-01-01

The autoradiography of a colony of Ps.a. which has been transferred, during growth, on a medium added with polymyxin and tritiate leucin makes it possible to locate an upper zone with a high metabolic activity and a basal zone with no metabolic activity. The latter, which consist of lysed cells, acts probably as a selective filter against the drug [fr

NOAA TIFF Image - 3m Bathymetric Rugosity, Florida Deep Coral Areas - Lost Coast Explorer - (2011), UTM 17N NAD83

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains a unified GeoTiff with 3x3 meter cell size representing the rugosity of several deep coral priority areas off the Atlantic Coast of Florida,...

Inhibition and dispersal of Agrobacterium tumefaciens biofilms by a small diffusible Pseudomonas aeruginosa exoproduct(s).

Science.gov (United States)

Hibbing, Michael E; Fuqua, Clay

2012-06-01

Environmental biofilms often contain mixed populations of different species. In these dense communities, competition between biofilm residents for limited nutrients such as iron can be fierce, leading to the evolution of competitive factors that affect the ability of competitors to grow or form biofilms. We have discovered a compound(s) present in the conditioned culture fluids of Pseudomonas aeruginosa that disperses and inhibits the formation of biofilms produced by the facultative plant pathogen Agrobacterium tumefaciens. The inhibitory activity is strongly induced when P. aeruginosa is cultivated in iron-limited conditions, but it does not function through iron sequestration. In addition, the production of the biofilm inhibitory activity is not regulated by the global iron regulatory protein Fur, the iron-responsive extracytoplasmic function σ factor PvdS, or three of the recognized P. aeruginosa quorum-sensing systems. In addition, the compound(s) responsible for the inhibition and dispersal of A. tumefaciens biofilm formation is likely distinct from the recently identified P. aeruginosa dispersal factor, cis-2-decenoic acid (CDA), as dialysis of the culture fluids showed that the inhibitory compound was larger than CDA and culture fluids that dispersed and inhibited biofilm formation by A. tumefaciens had no effect on biofilm formation by P. aeruginosa.

Chaotic Artificial Bee Colony Algorithm for System Identification of a Small-Scale Unmanned Helicopter

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Li Ding

2015-01-01

Full Text Available The purpose of this paper is devoted to developing a chaotic artificial bee colony algorithm (CABC for the system identification of a small-scale unmanned helicopter state-space model in hover condition. In order to avoid the premature of traditional artificial bee colony algorithm (ABC, which is stuck in local optimum and can not reach the global optimum, a novel chaotic operator with the characteristics of ergodicity and irregularity was introduced to enhance its performance. With input-output data collected from actual flight experiments, the identification results showed the superiority of CABC over the ABC and the genetic algorithm (GA. Simulations are presented to demonstrate the effectiveness of our proposed algorithm and the accuracy of the identified helicopter model.

NOAA TIFF Image - 3m Bathymetric Rugosity, Florida Deep Coral Areas (Miami) - Lost Coast Explorer - (2011), UTM 17N NAD83

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains a unified GeoTiff with 3x3 meter cell size representing the rugosity of several deep coral priority areas off the Atlantic Coast of Florida,...

Detection of Chloramphenicol Resistance Genes (cat in Clinical Isolates of Pseudomonas aeruginosa with Polymerase Chain Reaction Method

Directory of Open Access Journals (Sweden)

Tiana Milanda

2014-12-01

Full Text Available Pseudomonas aeruginosa is an opportunistic Gram negative bacteria, which may cause infection in eyes, ears, skin, bones, central nervous system, gastrointestinal tract, circulatory system, heart, respiratory system, and urinary tract. Recently, chloramphenicol is no longer used as the main option of the therapy due of its resistance case. The aim of this research was to detect the presence of gene which is responsible to chloramphenicol resistance in clinical isolates of P.aeruginosa. These bacteria isolated from pus of external otitis patients in Hasan Sadikin Hospital in Bandung City. Polymerase Chain Reaction (PCR method (colony-PCR and DNA-PCR were performed to detect this resistance gene. Electropherogram from PCR products showed that the chloramphenicol resistance in clinical isolates of P. aeruginosa was caused by cat gene (317 bp. Based on this research, cat gene may be used to detect the chloramphenicol resistance in patients with external ostitis.

Face Masks and Cough Etiquette Reduce the Cough Aerosol Concentration of Pseudomonas aeruginosa in People with Cystic Fibrosis.

Science.gov (United States)

Wood, Michelle E; Stockwell, Rebecca E; Johnson, Graham R; Ramsay, Kay A; Sherrard, Laura J; Jabbour, Nassib; Ballard, Emma; O'Rourke, Peter; Kidd, Timothy J; Wainwright, Claire E; Knibbs, Luke D; Sly, Peter D; Morawska, Lidia; Bell, Scott C

2018-02-01

People with cystic fibrosis (CF) generate Pseudomonas aeruginosa in droplet nuclei during coughing. The use of surgical masks has been recommended in healthcare settings to minimize pathogen transmission between patients with CF. To determine if face masks and cough etiquette reduce viable P. aeruginosa aerosolized during coughing. Twenty-five adults with CF and chronic P. aeruginosa infection were recruited. Participants performed six talking and coughing maneuvers, with or without face masks (surgical and N95) and hand covering the mouth when coughing (cough etiquette) in an aerosol-sampling device. An Andersen Cascade Impactor was used to sample the aerosol at 2 meters from each participant. Quantitative sputum and aerosol bacterial cultures were performed, and participants rated the mask comfort levels during the cough maneuvers. During uncovered coughing (reference maneuver), 19 of 25 (76%) participants produced aerosols containing P. aeruginosa, with a positive correlation found between sputum P. aeruginosa concentration (measured as cfu/ml) and aerosol P. aeruginosa colony-forming units. There was a reduction in aerosol P. aeruginosa load during coughing with a surgical mask, coughing with an N95 mask, and cough etiquette compared with uncovered coughing (P masks during coughing; yet, participants rated the surgical masks as more comfortable (P = 0.013). Cough etiquette provided approximately half the reduction of viable aerosols of the mask interventions during voluntary coughing. Talking was a low viable aerosol-producing activity. Face masks reduce cough-generated P. aeruginosa aerosols, with the surgical mask providing enhanced comfort. Cough etiquette was less effective at reducing viable aerosols.

Recent advances in the treatment of Pseudomonas aeruginosa infections in cystic fibrosis

DEFF Research Database (Denmark)

Høiby, Niels

2011-01-01

Chronic Pseudomonas aeruginosa lung infection in cystic fibrosis (CF) patients is caused by biofilm-growing mucoid strains. Biofilms can be prevented by early aggressive antibiotic prophylaxis or therapy, and they can be treated by chronic suppressive therapy. New results from one small trial sug...... patients without P. aeruginosa infection did not improve lung function. Here I review the recent advances in the treatment of P. aeruginosa lung infections with a focus on inhalation treatments targeted at prophylaxis and chronic suppressive therapy....

Assessing the disturbance potential of small unoccupied aircraft systems (UAS on gray seals (Halichoerus grypus at breeding colonies in Nova Scotia, Canada

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Lauren Arona

2018-03-01

Full Text Available The use of small unoccupied aircraft systems (UAS for ecological studies and wildlife population assessments is increasing. These methods can provide significant benefits in terms of costs and reductions in human risk, but little is known if UAS-based approaches cause disturbance of animals during operations. To address this knowledge gap, we conducted a series of UAS flights at gray seal breeding colonies on Hay and Saddle Islands in Nova Scotia, Canada. Using a small fixed-wing UAS, we assessed both immediate and short-term effects of surveys using sequential image analysis and between-flight seal counts in ten, 50 m2 random quadrats at each colony. Counts of adult gray seals and young-of-the-year animals between first and second flights revealed no changes in abundance in quadrats (matched pair t-test p > 0.69 and slopes approaching 1 for linear regression comparisons (r2 > 0.80. Sequential image analysis revealed no changes in orientation or posture of imaged animals. We also assessed the acoustic properties of the small UAS in relation to low ambient noise conditions using sound equivalent level (Leq measurements with a calibrated U-MIK 1 and a 1/3 octave band soundscape approach. The results of Leq measurements indicate that small fixed-wing UAS are quiet, with most energy above 160 Hz, and that levels across 1/3 octave bands do not greatly exceed ambient acoustic measurements in a quiet field during operations at standard survey altitudes. As such, this platform is unlikely to acoustically disturb gray seals at breeding colonies during population surveys. The results of the present study indicate that the effects of small fixed-wing UAS on gray seals at breeding colonies are negligible, and that fixed-wing UAS-based approaches should be considered amongst best practices for assessing gray seal colonies.

Rugosity 10 m grid derived from gridded bathymetry of Farallon de Pajaros (Uracas) Island, Commonwealth of the Northern Mariana Islands (CNMI), USA

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Rugosity is derived from gridded (10 m cell size) multibeam bathymetry, collected aboard NOAA Ship Hiialaka'i and R/V AHI, using the Benthic Terrain Modeler with...

Gene expression in Pseudomonas aeruginosa swarming motility

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Déziel Eric

2010-10-01

Full Text Available Abstract Background The bacterium Pseudomonas aeruginosa is capable of three types of motilities: swimming, twitching and swarming. The latter is characterized by a fast and coordinated group movement over a semi-solid surface resulting from intercellular interactions and morphological differentiation. A striking feature of swarming motility is the complex fractal-like patterns displayed by migrating bacteria while they move away from their inoculation point. This type of group behaviour is still poorly understood and its characterization provides important information on bacterial structured communities such as biofilms. Using GeneChip® Affymetrix microarrays, we obtained the transcriptomic profiles of both bacterial populations located at the tip of migrating tendrils and swarm center of swarming colonies and compared these profiles to that of a bacterial control population grown on the same media but solidified to not allow swarming motility. Results Microarray raw data were corrected for background noise with the RMA algorithm and quantile normalized. Differentially expressed genes between the three conditions were selected using a threshold of 1.5 log2-fold, which gave a total of 378 selected genes (6.3% of the predicted open reading frames of strain PA14. Major shifts in gene expression patterns are observed in each growth conditions, highlighting the presence of distinct bacterial subpopulations within a swarming colony (tendril tips vs. swarm center. Unexpectedly, microarrays expression data reveal that a minority of genes are up-regulated in tendril tip populations. Among them, we found energy metabolism, ribosomal protein and transport of small molecules related genes. On the other hand, many well-known virulence factors genes were globally repressed in tendril tip cells. Swarm center cells are distinct and appear to be under oxidative and copper stress responses. Conclusions Results reported in this study show that, as opposed to

Colony Dimorphism in Bradyrhizobium Strains

Science.gov (United States)

Sylvester-Bradley, Rosemary; Thornton, Philip; Jones, Peter

1988-01-01

Ten isolates of Bradyrhizobium spp. which form two colony types were studied; the isolates originated from a range of legume species. The two colony types differed in the amount of gum formed or size or both, depending on the strain. Whole 7-day-old colonies of each type were subcultured to determine the proportion of cells which had changed to the other type. An iterative computerized procedure was used to determine the rate of switching per generation between the two types and to predict proportions reached at equilibrium for each strain. The predicted proportions of the wetter (more gummy) or larger colony type at equilibrium differed significantly between strains, ranging from 0.9999 (strain CIAT 2383) to 0.0216 (strain CIAT 2469), because some strains switched faster from dry to wet (or small to large) and others switched faster from wet to dry (or large to small). Predicted equilibrium was reached after about 140 generations in strain USDA 76. In all but one strain (CIAT 3030) the growth rate of the wetter colony type was greater than or similar to that of the drier type. The mean difference in generation time between the two colony types was 0.37 h. Doubling times calculated for either colony type after 7 days of growth on the agar surface ranged from 6.0 to 7.3 h. The formation of two persistent colony types by one strain (clonal or colony dimorphism) may be a common phenomenon among Bradyrhizobium strains. Images PMID:16347599

Novel drug targets in cell wall biosynthesis exploited by gene disruption in Pseudomonas aeruginosa.

Science.gov (United States)

Elamin, Ayssar A; Steinicke, Susanne; Oehlmann, Wulf; Braun, Yvonne; Wanas, Hanaa; Shuralev, Eduard A; Huck, Carmen; Maringer, Marko; Rohde, Manfred; Singh, Mahavir

2017-01-01

For clinicians, Pseudomonas aeruginosa is a nightmare pathogen that is one of the top three causes of opportunistic human infections. Therapy of P. aeruginosa infections is complicated due to its natural high intrinsic resistance to antibiotics. Active efflux and decreased uptake of drugs due to cell wall/membrane permeability appear to be important issues in the acquired antibiotic tolerance mechanisms. Bacterial cell wall biosynthesis enzymes have been shown to be essential for pathogenicity of Gram-negative bacteria. However, the role of these targets in virulence has not been identified in P. aeruginosa. Here, we report knockout (k.o) mutants of six cell wall biosynthesis targets (murA, PA4450; murD, PA4414; murF, PA4416; ppiB, PA1793; rmlA, PA5163; waaA, PA4988) in P. aeruginosa PAO1, and characterized these in order to find out whether these genes and their products contribute to pathogenicity and virulence of P. aeruginosa. Except waaA k.o, deletion of cell wall biosynthesis targets significantly reduced growth rate in minimal medium compared to the parent strain. The k.o mutants showed exciting changes in cell morphology and colonial architectures. Remarkably, ΔmurF cells became grossly enlarged. Moreover, the mutants were also attenuated in vivo in a mouse infection model except ΔmurF and ΔwaaA and proved to be more sensitive to macrophage-mediated killing than the wild-type strain. Interestingly, the deletion of the murA gene resulted in loss of virulence activity in mice, and the virulence was restored in a plant model by unknown mechanism. This study demonstrates that cell wall targets contribute significantly to intracellular survival, in vivo growth, and pathogenesis of P. aeruginosa. In conclusion, these findings establish a link between cell wall targets and virulence of P. aeruginosa and thus may lead to development of novel drugs for the treatment of P. aeruginosa infection.

Chasing your honey: Worldwide diaspora of the small hive beetle, a parasite of honey bee colonies

Science.gov (United States)

Endemic to sub-Saharan Africa, small hive beetles (Aethina tumida) are now an invasive pest of honey bee colonies in Australia and North America. Knowledge on the introduction(s) from Africa into and between the current ranges will shed light on pest populations, invasion pathways and contribute to ...

PFGE and antibiotic susceptibility phenotype analysis of Pseudomonas aeruginosa strain chronically infecting Cystic Fibrosis patients

Directory of Open Access Journals (Sweden)

Giovanna Pulcrano

2008-09-01

Full Text Available Pseudomonas aeruginosa is the leading cause of chronic lung infection and following pulmonary worsening of cystic fibrosis patients. To verify whether bacterial modifications regarding motility, mucoidy, and serum susceptibility proceeded from an adaptation to chronic infection or a replacement with a new strain, sequential P. aeruginosa isolates of known phenotype collected from 5 cystic fibrosis patients were typed by pulsed-field gel electophoresis (PFGE. Antimicrobial susceptibility testing of all isolates was performed by the disc diffusion method. PFGE typing demonstrated that strains dissimilar in colony morphotype and of different antibiotic susceptibility patterns could be of the same genotype. Some patients were colonized with a rather constant P. aeruginosa flora, with strains of different phenotypes but of one genotype. Instead, some patients may be colonized by more than one genotype. Secretion of mucoid exopolysaccharide and acquisition of a new antibiotic susceptibility phenotype in these strain appear to evolve during chronic colonization in cystic fibrosis patients from specific adaptation to infection rather than from acquisition of new bacterial strains.

Immune Modulating Topical S100A8/A9 Inhibits Growth of Pseudomonas aeruginosa and Mitigates Biofilm Infection in Chronic Wounds

DEFF Research Database (Denmark)

Trøstrup, Hannah; Lerche, Christian Johann; Christophersen, Lars

2017-01-01

in a murine model and P. aeruginosa growth in vitro. Seventy-six mice, inflicted with a full-thickness burn wound were challenged subcutaneously (s.c.) by 10⁶ colony-forming units (CFUs) of P. aeruginosa biofilm. Mice were subsequently randomized into two treatment groups, one group receiving recombinant...... murine S100A8/A9 and a group of vehicle controls (phosphate-buffered saline, PBS) all treated with s.c. injections daily for up to five days. Wounds were analyzed for quantitative bacteriology and contents of key inflammatory markers. Count of blood polymorphonuclear leukocytes was included. S100A8/A9...

Zingiber officinale: Its antibacterial activity on Pseudomonas aeruginosa and mode of action evaluated by flow cytometry.

Science.gov (United States)

Chakotiya, Ankita Singh; Tanwar, Ankit; Narula, Alka; Sharma, Rakesh Kumar

2017-06-01

Biofilm formation, low membrane permeability and efflux activity developed by Pseudomonas aeruginosa, play an important role in the mechanism of infection and antimicrobial resistance. In the present study we evaluate the antibacterial effect of Zingiber officinale against multi-drug resistant strain of P. aeruginosa. The study explores antibacterial efficacy and time-kill study concomitantly the effect of herbal extract on bacterial cell physiology with the use of flow cytometry and inhibition of biofilm formation. Z. officinale was found to inhibit the growth of P. aeruginosa, significantly. A major decline in the Colony Forming Units was observed with 3 log 10  at 12 h of treatment. Also it is found to affect the membrane integrity of the pathogen, as 70.06 ± 2.009% cells were found to stain with Propidium iodide. In case of efflux activity 86.9 ± 2.08% cells were found in Ethidium bromide positive region. Biofilm formation inhibition ability was found in the range of 68.13 ± 4.11% to 84.86 ± 2.02%. Z.officinale is effective for killing Multi-Drug Resistant P. aeruginosa clinical isolate by affecting the cellular physiology and inhibiting the biofilm formation. Copyright © 2017 Elsevier Ltd. All rights reserved.

QUALIDADE BACTERIOLÓGICA DE OVOS CONTAMINADOS COM PSEUDOMONAS AERUGINOSA E ARMAZENADOS EM TEMPERATURA AMBIENTE OU REFRIGERADOS

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Fernanda Rodrigues Mendes

2014-12-01

Full Text Available The aim of this study was to evaluate the effect of sanitization and storage temperature on the quality of commercial eggs inoculated with Pseudomonas aeruginosa. We used 240 large eggs, without cracks, from Dekalb White laying hens at 30 to 40 weeks of age. The experimental design used was two blocks in a 2 x 2 factorial arrange (washed/non-washed and refrigerated/non-refrigerated with twelve replicates. The eggs were contaminated by handling, with 1.5 x 105 colony-forming units (CFU of Pseudomonas aeruginosa and stored at 5 °C and 25 °C for 30 days. Each ten days the eggshell and contents were submitted to bacteriological analyses. Variance analyses were performed and the data were compared by Tukey test. The results showed that Pseudomonas aeruginosa were isolated from the shells and contents of all eggs. Therefore, when the eggs were sanitized and stored at 5 ºC the contamination was less intense. The correlation between the presences of Pseudomonas aeruginosa in the shell and contents was high, when the eggs were not sanitized nor refrigerated. The conclusion of this study was that the egg must be sanitized and refrigerated when the stored for more than 30 days.

Colony formation in the cyanobacterium Microcystis.

Science.gov (United States)

Xiao, Man; Li, Ming; Reynolds, Colin S

2018-02-22

Morphological evolution from a unicellular to multicellular state provides greater opportunities for organisms to attain larger and more complex living forms. As the most common freshwater cyanobacterial genus, Microcystis is a unicellular microorganism, with high phenotypic plasticity, which forms colonies and blooms in lakes and reservoirs worldwide. We conducted a systematic review of field studies from the 1990s to 2017 where Microcystis was dominant. Microcystis was detected as the dominant genus in waterbodies from temperate to subtropical and tropical zones. Unicellular Microcystis spp. can be induced to form colonies by adjusting biotic and abiotic factors in laboratory. Colony formation by cell division has been induced by zooplankton filtrate, high Pb 2+ concentration, the presence of another cyanobacterium (Cylindrospermopsis raciborskii), heterotrophic bacteria, and by low temperature and light intensity. Colony formation by cell adhesion can be induced by zooplankton grazing, high Ca 2+ concentration, and microcystins. We hypothesise that single cells of all Microcystis morphospecies initially form colonies with a similar morphology to those found in the early spring. These colonies gradually change their morphology to that of M. ichthyoblabe, M. wesenbergii and M. aeruginosa with changing environmental conditions. Colony formation provides Microcystis with many ecological advantages, including adaption to varying light, sustained growth under poor nutrient supply, protection from chemical stressors and protection from grazing. These benefits represent passive tactics responding to environmental stress. Microcystis colonies form at the cost of decreased specific growth rates compared with a unicellular habit. Large colony size allows Microcystis to attain rapid floating velocities (maximum recorded for a single colony, ∼ 10.08 m h -1 ) that enable them to develop and maintain a large biomass near the surface of eutrophic lakes, where they may shade

Pseudomonas aeruginosa induces pigment production and enhances virulence in a white phenotypic variant of Staphylococcus aureus.

Science.gov (United States)

Antonic, Vlado; Stojadinovic, Alexander; Zhang, Binxue; Izadjoo, Mina J; Alavi, Mohammad

2013-01-01

Staphyloxanthin is a virulence factor which protects Staphylococcus aureus in stress conditions. We isolated two pigment variants of S. aureus and one strain of Pseudomonas aeruginosa from a single wound infection. S. aureus variants displayed white and yellow colony phenotypes. The sequence of the operons for staphyloxanthin synthesis indicated that coding and promoter regions were identical between the two pigment variants. Quorum sensing controls pigment synthesis in some bacteria. It is also shown that P. aeruginosa quorum-sensing molecules affect S. aureus transcription. We explored whether the co-infecting P. aeruginosa can affect pigment production in the white S. aureus variant. In co-culture experiments between the white variants and a selected number of Gram-positive and Gram-negative bacteria, only P. aeruginosa induced pigment production in the white variant. Gene expression analysis of the white variant did not indicate upregulation of the crtM and other genes known to be involved in pigment production (sigB, sarA, farnesyl pyrophosphate synthase gene [FPP-synthase], hfq). In contrast, transcription of the catalase gene was significantly upregulated after co-culture. P. aeruginosa-induced pigment synthesis and catalase upregulation correlated with increased resistance to polymyxin B, hydrogen peroxide, and the intracellular environment of macrophages. Our data indicate the presence of silent but functional staphyloxanthin synthesis machinery in a white phenotypic variant of S. aureus which is activated by a co-infecting P. aeruginosa via inter-species communication. Another S. aureus virulence factor, catalase is also induced by this co-infecting bacterium. The resulting phenotypic changes are directly correlated with resistance of the white variant to stressful conditions.

Epidemiology of Pseudomonas aeruginosa in cystic fibrosis and the possible role of contamination by dental equipment

DEFF Research Database (Denmark)

Jensen, E T; Giwercman, B; Ojeniyi, B

1997-01-01

Cystic fibrosis (CF) patients often suffer from Pseudomonas aeruginosa lung infection yet the source of this organism is not known. In order to determine whether CF patients might be contaminated with P. aeruginosa from dental equipment, a total of 103 water samples from 25 dental sessions...... samples (5.5%) from nine sessions (11%) were positive for P. aeruginosa. In one case, genotypically identical (RFLP, pulsed-field gel electrophoresis) P. aeruginosa strains were found both in water from the dental equipment and in the CF patients sputum. This indicates a small risk for acquiring P...

NOAA TIFF Image - 10m Bathymetric Rugosity, South Atlantic Bight - Deep Coral Priority Areas - NOAA Ship Nancy Foster - (2007), UTM 17N NAD83

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains a unified GeoTiff with 10x10 meter cell size representing the rugosity of several deep coral priority areas off the South Atlantic Bight,...

Study of anti mutagenic and mutagenic effect of different chemicals on clinically isolated strains of pseudomonas aeruginosa

International Nuclear Information System (INIS)

Qureshi, A.M.; Durrani, F.; Janjua, M.

1994-01-01

This project was undertaken to study the effect of twelve different compounds to test their anti mutagenic and mutagenic activity against clinically isolated strains of Pseudomonas aeruginosa. The effect of these compounds was estimated by counting the number of rifampicin resistant colonies growing in a particular time in a compound. The results were interpreted by plotting graphs between 10g N/NO (Rif R Colonies/ ml) and time to estimate the forward mutation rat. The results revealed that acridine, Basic fuchsin, Caffeine, cycloheximide, Ethidium bromide and Histidine probably have an anti mutagenic effect, while Cysteine, folic acid, Ethyl methane, suplphonate, Manganous Chloride and N-nitrosodietylamine acted as mutagen. Ecoli was used as control through out the study. (author)

CARBONIFEROUS CORALS AND CHAETETIDS FROM EXOTIC LIMESTONE BLOCK OF THE CRIMEA

OpenAIRE

OGAR, VICTOR; KLEVTSOVSKYI, ANDREY

2015-01-01

A chaetetid sponge and coral fauna from a Carboniferous exotic limestone block in the Lower Jurassic Esciorda olistostrome on the Bodrak River (Crimean Mountains) are described for the first time. The Bodrak exotic block is composed of massive limestone. It contains the chaetetid Chaetetes (Boswellia) sp., the tabulate coral Multithecopora sp., and poorly preserved rugose corals, including Dibunophyllum? sp., Cordibia? sp. and gen. et sp. indet. Only the fasciculate colonies of the rugose cor...

Relative contribution of Prevotella intermedia and Pseudomonas aeruginosa to lung pathology in airways of patients with cystic fibrosis.

Science.gov (United States)

Ulrich, Martina; Beer, Isabelle; Braitmaier, Peter; Dierkes, Michaela; Kummer, Florian; Krismer, Bernhard; Schumacher, Ulrike; Gräpler-Mainka, Ute; Riethmüller, Joachim; Jensen, Peter Ø; Bjarnsholt, Thomas; Høiby, Niels; Bellon, Gabriel; Döring, Gerd

2010-11-01

Patients with cystic fibrosis (CF) with Pseudomonas aeruginosa lung infections produce endobronchial mucus plugs allowing growth of obligate anaerobes including Prevotella spp. Whether obligate anaerobes contribute to the pathophysiology of CF lung disease is unknown. The virulence of Prevotella intermedia and Ps aeruginosa was investigated in vitro and in mice, antibodies against P intermedia in CF sera were assessed and a culture-independent detection method for P intermedia/P nigrescens in CF sputum was tested. P intermedia reached cell numbers of >10(5)->10(7) colony-forming units (CFU)/ml sputum. The majority of patients with CF (16/17; 94.1%) produced antibodies against two immunoreactive antigens of P intermedia. Culture supernatant fluids, collected from 10(9) P intermedia cells, were more cytotoxic to respiratory epithelial cells in vitro and inflammatory in mouse lungs than respective fluids from anaerobically grown Ps aeruginosa, while fluids from aerobically grown Ps aeruginosa had the highest cytotoxicity and inflammation. Both pathological effects were largely reduced when culture supernatant fluids from 10(7) cells of either species were used. P intermedia cells (∼10(6)CFU/lung) did not induce mortality in the agar beads lung infection mouse model, while Ps aeruginosa cells caused death in 30% of mice due to rapid multiplication. A P intermedia/P nigrescens-specific PNA probe was significantly more sensitive than culture-dependent diagnostic assays to detect these strict anaerobes. Ps aeruginosa and P intermedia become significantly virulent in vitro and in vivo when cell numbers exceed 10(8) CFU/lung.

Efficacy of an entomopathogenic fungus, Isaria fumosorosea and an insect growth regulator against the rugose spiraling whitefly, Aleurodicus rugioperculatus Martin (Hemiptera: Aleyrodidae)

Science.gov (United States)

Aleurodicus rugioperculatus Martin, infamous as gumbo limbo or rugose spiraling whitefly is a new addition in the list of devastating whitefly species found in Florida. It is a newly introduced pest of Central American origin, reported first time in Florida from Miami-Dade County in 2009. Since then...

Bacterial recovery using sonication versus swabbing of titanium and stainless steel implants inoculated with Staphylococcus pseudintermedius or Pseudomonas aeruginosa.

Science.gov (United States)

Keeshen, Thomas; Case, J Brad; Wellehan, James F; Dujowich, Mauricio

2017-09-12

To evaluate the use of sonication to improve recovery of bacteria from metal discs infected with bacteria commonly associated with implant infections in veterinary medicine. In vitro study in which sterile titanium (Ti6Al4V) and stainless steel (AIS1316-L) discs were incubated with either Staphylococcus pseudintermedius or Pseudomonas aeruginosa for 24 hours. The following three groups were compared: 1) the sonication group involved immersing the discs in sterile saline and sonicating for five minutes; 2) the sham group was considered a negative control in which the discs were immersed in saline for five minutes without sonication; and 3) the swab group involved systematically swabbing the implant with a sterile culturette. All samples were plated on blood agar and incubated for 24 hours. Colonies were then counted and compared. For both species of bacteria, there was a significant increase in bacterial colonies isolated using sonication compared to the other two study groups (p = 0.0001). No differences in bacterial growth were found between the two types of metal implants. There was a significant increase in bacterial colony counts for S. pseudintermedius when comparing the swab group versus the sham group, but this was not significant for P. aeruginosa. Sonication significantly improves recovery of bacteria commonly associated with veterinary implant-associated surgical site infections compared to swabbing of implants in vitro. A prospective clinical evaluation is indicated to determine the in vivo efficacy of sonication in veterinary patients.

A Rapid Phenotypic Whole Cell Screening Approach for the Identification of Small Molecule Inhibitors that Counter Beta-lactamase Resistance in Pseudomonas aeruginosa

Science.gov (United States)

Collia, Deanna; Bannister, Thomas D.; Tan, Hao; Jin, Shouguang; Langaee, Taimour; Shumate, Justin; Scampavia, Louis; Spicer, Timothy P.

2017-01-01

Pseudomonas aeruginosa is an opportunistic human pathogen which is prevalent in hospitals and continues to develop resistance to multiple classes of antibiotics. Historically, β-lactam antibiotics have been the first line of therapeutic defense. However, the emergence of multidrug-resistant (MDR) strains of P. aeruginosa, such as AmpC β-lactamase overproducing mutants, limits the effectiveness of current antibiotics. Among AmpC hyper producing clinical isolates, inactivation of AmpG, which is essential for the expression of AmpC, increases bacterial sensitivity to β-lactam antibiotics. We hypothesize that inhibition of AmpG activity will enhance the efficacy of β-lactams against P. aeruginosa. Here, using a highly drug resistant AmpC inducible laboratory strain PAO1, we describe an ultra-high throughput whole cell turbidity assay designed to identify small molecule inhibitors of the AmpG. We screened 645K compounds to identify compounds with the ability to inhibit bacterial growth in the presence of Cefoxitin; an AmpC inducer, and identified 2,663 inhibitors which were also tested in the absence of Cefoxitin to determine AmpG specificity. The Z′ and S:B were robust at 0.87 ± 0.05 and 2.2 ± 0.2, respectively. Through a series of secondary and tertiary studies, including a novel luciferase based counterscreen, we ultimately identified 8 potential AmpG specific inhibitors. PMID:28850797

Facultative control of matrix production optimizes competitive fitness in Pseudomonas aeruginosa PA14 biofilm models.

Science.gov (United States)

Madsen, Jonas S; Lin, Yu-Cheng; Squyres, Georgia R; Price-Whelan, Alexa; de Santiago Torio, Ana; Song, Angela; Cornell, William C; Sørensen, Søren J; Xavier, Joao B; Dietrich, Lars E P

2015-12-01

As biofilms grow, resident cells inevitably face the challenge of resource limitation. In the opportunistic pathogen Pseudomonas aeruginosa PA14, electron acceptor availability affects matrix production and, as a result, biofilm morphogenesis. The secreted matrix polysaccharide Pel is required for pellicle formation and for colony wrinkling, two activities that promote access to O2. We examined the exploitability and evolvability of Pel production at the air-liquid interface (during pellicle formation) and on solid surfaces (during colony formation). Although Pel contributes to the developmental response to electron acceptor limitation in both biofilm formation regimes, we found variation in the exploitability of its production and necessity for competitive fitness between the two systems. The wild type showed a competitive advantage against a non-Pel-producing mutant in pellicles but no advantage in colonies. Adaptation to the pellicle environment selected for mutants with a competitive advantage against the wild type in pellicles but also caused a severe disadvantage in colonies, even in wrinkled colony centers. Evolution in the colony center produced divergent phenotypes, while adaptation to the colony edge produced mutants with clear competitive advantages against the wild type in this O2-replete niche. In general, the structurally heterogeneous colony environment promoted more diversification than the more homogeneous pellicle. These results suggest that the role of Pel in community structure formation in response to electron acceptor limitation is unique to specific biofilm models and that the facultative control of Pel production is required for PA14 to maintain optimum benefit in different types of communities. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

JAX Colony Management System (JCMS): an extensible colony and phenotype data management system

OpenAIRE

Donnelly, Chuck J.; McFarland, Mike; Ames, Abigail; Sundberg, Beth; Springer, Dave; Blauth, Peter; Bult, Carol J.

2010-01-01

The Jackson Laboratory Colony Management System (JCMS) is a software application for managing data and information related to research mouse colonies, associated biospecimens, and experimental protocols. JCMS runs directly on computers that run one of the PC Windows® operating systems, but can be accessed via web browser interfaces from any computer running a Windows, Macintosh®, or Linux® operating system. JCMS can be configured for a single user or multiple users in small- to medium-size wo...

Evolution of antibiotic resistance in biofilm and planktonic P. aeruginosa populations exposed to sub-inhibitory levels of ciprofloxacin

DEFF Research Database (Denmark)

Ahmed, Marwa N.; Porse, Andreas; Sommer, Morten Otto Alexander

2018-01-01

in planktonic cultures and are less studied in biofilms. We experimentally evolved P. aeruginosa PAO1 colony-biofilms and stationary-phase planktonic cultures for seven passages in the presence of sub-inhibitory levels (0.1 mg/L) of ciprofloxacin (CIP) and performed a genotypic (whole bacterial population......The opportunistic Gram-negative pathogen Pseudomonas aeruginosa, known for its intrinsic and acquired antibiotic resistance, has a notorious ability to form biofilms, which often facilitate chronic infections. The evolutionary paths to antibiotic resistance have mainly been investigated......-dependent adaptations. A general trend towards a reduction in type IV-pili dependent motility (twitching) in CIP-evolved populations, and towards loss of virulence associated traits in the populations evolved in the absence of antibiotic, was observed. In conclusion, our data indicate that biofilms facilitate...

A case report of Small Colony variant of Staphylococcus aureus isolated from a patient with chronic oesteomyelitis in a tertiary care hospital of eastern India

Directory of Open Access Journals (Sweden)

Kalidas Rit

2014-01-01

Full Text Available Small colony variants (SCVs of Staphylococcus aureus often cause persistant and relapsing infections. SCVs are characterized by a strong reduction in growth rate, atypical colony morphology and unusual biochemical characteristics. We here report a case of chronic oesteomyelitis caused by SCV of Staphyloccous aureus in a middle aged male patient.

JAX Colony Management System (JCMS): an extensible colony and phenotype data management system.

Science.gov (United States)

Donnelly, Chuck J; McFarland, Mike; Ames, Abigail; Sundberg, Beth; Springer, Dave; Blauth, Peter; Bult, Carol J

2010-04-01

The Jackson Laboratory Colony Management System (JCMS) is a software application for managing data and information related to research mouse colonies, associated biospecimens, and experimental protocols. JCMS runs directly on computers that run one of the PC Windows operating systems, but can be accessed via web browser interfaces from any computer running a Windows, Macintosh, or Linux operating system. JCMS can be configured for a single user or multiple users in small- to medium-size work groups. The target audience for JCMS includes laboratory technicians, animal colony managers, and principal investigators. The application provides operational support for colony management and experimental workflows, sample and data tracking through transaction-based data entry forms, and date-driven work reports. Flexible query forms allow researchers to retrieve database records based on user-defined criteria. Recent advances in handheld computers with integrated barcode readers, middleware technologies, web browsers, and wireless networks add to the utility of JCMS by allowing real-time access to the database from any networked computer.

Vaccines for preventing infection with Pseudomonas aeruginosa in cystic fibrosis.

Science.gov (United States)

Johansen, Helle Krogh; Gøtzsche, Peter C

2015-08-23

Chronic pulmonary infection in cystic fibrosis results in progressive lung damage. Once colonisation of the lungs with Pseudomonas aeruginosa occurs, it is almost impossible to eradicate. Vaccines, aimed at reducing infection with Pseudomonas aeruginosa, have been developed. This is an update of a previously published review. To assess the effectiveness of vaccination against Pseudomonas aeruginosa in cystic fibrosis. We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register using the terms vaccines AND pseudomonas (last search 30 March 2015). We previously searched PubMed using the terms vaccin* AND cystic fibrosis (last search 30 May 2013). Randomised trials (published or unpublished) comparing Pseudomonas aeruginosa vaccines (oral, parenteral or intranasal) with control vaccines or no intervention in cystic fibrosis. The authors independently selected trials, assessed them and extracted data. Six trials were identified. Two trials were excluded since they were not randomised and one old, small trial because it was not possible to assess whether is was randomised. The three included trials comprised 483, 476 and 37 patients, respectively. No data have been published from one of the large trials, but the company stated in a press release that the trial failed to confirm the results from an earlier study and that further clinical development was suspended. In the other large trial, relative risk for chronic infection was 0.91 (95% confidence interval 0.55 to 1.49), and in the small trial, the risk was also close to one. In the large trial, one patient was reported to have died in the observation period. In that trial, 227 adverse events (4 severe) were registered in the vaccine group and 91 (1 severe) in the control group. In this large trial of a vaccine developed against flagella antigens, antibody titres against the epitopes contained in the vaccine were higher in the vaccine group compared to the placebo group (P Vaccines against

Activation of the SOS response increases the frequency of small colony variants

DEFF Research Database (Denmark)

Vestergaard, Martin; Paulander, Wilhelm Erik Axel; Ingmer, Hanne

2015-01-01

BACKGROUND: In Staphylococcus aureus sub-populations of slow-growing cells forming small colony variants (SCVs) are associated with persistent and recurrent infections that are difficult to eradicate with antibiotic therapies. In SCVs that are resistant towards aminoglycosides, mutations have been...... with different mechanism of action influence the formation of SCVs that are resistant to otherwise lethal concentrations of the aminoglycoside, gentamicin. We found that exposure of S. aureus to fluoroquinolones and mitomycin C increased the frequency of gentamicin resistant SCVs, while other antibiotic classes...... failed to do so. The higher proportion of SCVs in cultures exposed to fluoroquinolones and mitomycin C compared to un-exposed cultures correlate with an increased mutation rate monitored by rifampicin resistance and followed induction of the SOS DNA damage response. CONCLUSION: Our observations suggest...

Highly plastic genome of Microcystis aeruginosa PCC 7806, a ubiquitous toxic freshwater cyanobacterium

Directory of Open Access Journals (Sweden)

Latifi Amel

2008-06-01

Full Text Available Abstract Background The colonial cyanobacterium Microcystis proliferates in a wide range of freshwater ecosystems and is exposed to changing environmental factors during its life cycle. Microcystis blooms are often toxic, potentially fatal to animals and humans, and may cause environmental problems. There has been little investigation of the genomics of these cyanobacteria. Results Deciphering the 5,172,804 bp sequence of Microcystis aeruginosa PCC 7806 has revealed the high plasticity of its genome: 11.7% DNA repeats containing more than 1,000 bases, 6.8% putative transposases and 21 putative restriction enzymes. Compared to the genomes of other cyanobacterial lineages, strain PCC 7806 contains a large number of atypical genes that may have been acquired by lateral transfers. Metabolic pathways, such as fermentation and a methionine salvage pathway, have been identified, as have genes for programmed cell death that may be related to the rapid disappearance of Microcystis blooms in nature. Analysis of the PCC 7806 genome also reveals striking novel biosynthetic features that might help to elucidate the ecological impact of secondary metabolites and lead to the discovery of novel metabolites for new biotechnological applications. M. aeruginosa and other large cyanobacterial genomes exhibit a rapid loss of synteny in contrast to other microbial genomes. Conclusion Microcystis aeruginosa PCC 7806 appears to have adopted an evolutionary strategy relying on unusual genome plasticity to adapt to eutrophic freshwater ecosystems, a property shared by another strain of M. aeruginosa (NIES-843. Comparisons of the genomes of PCC 7806 and other cyanobacterial strains indicate that a similar strategy may have also been used by the marine strain Crocosphaera watsonii WH8501 to adapt to other ecological niches, such as oligotrophic open oceans.

Different tolerances to chemical contaminants between unicellular and colonial morph of Microcystis aeruginosa: excluding the differences among different strains.

Science.gov (United States)

Li, Ming; Nkrumah, Philip Nti; Peng, Qiang

2015-03-21

In order to ascertain the different tolerances to chemical contaminants in one strain of Microcystis with different morphology, unicellular and colonial Microcystis in one strain was obtained from different conditions of light intensity and temperature. The samples were divided into 8 groups including control (no chemical addition), CuSO4, chloromycetin, and linear alkylbenzene sulfonatelas (LAS) treatments. The cell density, cell viability, superoxide dismutase (SOD), and malonaldehyde of Microcystis were analyzed. It was observed that cell density of both unicellular and colonial Microcystis increased from the beginning to day-5 in the control and the CuSO4 treatments. However, the growth of Microcystis was significantly inhibited in the culture with chloromycetin and LAS treatments. Notably, the inhibition rate was significantly high in unicellular Microcystis relative to the colonial Microcystis. The esterase activity in all the treatments decreased dramatically relating to the control. In addition, the esterase activity in colonial Microcystis was significantly higher than that of the unicellular Microcystis in all the treatments. Although there were no significant differences in activities of SOD between the two morphologies in the control treatments, in all the other treatments, significant differences were observed. The results proved that colony formation of Microcystis could be considered as a strategy in response to chemical stress. Copyright © 2014 Elsevier B.V. All rights reserved.

Pseudomonas aeruginosa induces pigment production and enhances virulence in a white phenotypic variant of Staphylococcus aureus

Directory of Open Access Journals (Sweden)

Antonic V

2013-11-01

Full Text Available Vlado Antonic,1–3 Alexander Stojadinovic,3–5 Binxue Zhang,1–3 Mina J Izadjoo,1–3,5 Mohammad Alavi1–3 1Henry M Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, USA; 2Diagnostic and Translational Research Center, Gaithersburg, MD, USA; 3Combat Wound Initiative Program, Bethesda, MD, USA; 4Walter Reed National Military Medical Center, Bethesda, MD, USA; 5Uniformed Services University of the Health Sciences, Bethesda, MD, USA Abstract: Staphyloxanthin is a virulence factor which protects Staphylococcus aureus in stress conditions. We isolated two pigment variants of S. aureus and one strain of Pseudomonas aeruginosa from a single wound infection. S. aureus variants displayed white and yellow colony phenotypes. The sequence of the operons for staphyloxanthin synthesis indicated that coding and promoter regions were identical between the two pigment variants. Quorum sensing controls pigment synthesis in some bacteria. It is also shown that P. aeruginosa quorum-sensing molecules affect S. aureus transcription. We explored whether the co-infecting P. aeruginosa can affect pigment production in the white S. aureus variant. In co-culture experiments between the white variants and a selected number of Gram-positive and Gram-negative bacteria, only P. aeruginosa induced pigment production in the white variant. Gene expression analysis of the white variant did not indicate upregulation of the crtM and other genes known to be involved in pigment production (sigB, sarA, farnesyl pyrophosphate synthase gene [FPP-synthase], hfq. In contrast, transcription of the catalase gene was significantly upregulated after co-culture. P. aeruginosa-induced pigment synthesis and catalase upregulation correlated with increased resistance to polymyxin B, hydrogen peroxide, and the intracellular environment of macrophages. Our data indicate the presence of silent but functional staphyloxanthin synthesis machinery in a white phenotypic variant

Evolution of metabolic divergence in Pseudomonas aeruginosa during long-term infection facilitates a proto-cooperative interspecies interaction

DEFF Research Database (Denmark)

Frydenlund Michelsen, Charlotte; Khademi, Seyed Mohammad Hossein; Johansen, Helle Krogh

2016-01-01

The effect of polymicrobial interactions on pathogen physiology and how it can act either to limit pathogen colonization or to potentiate pathogen expansion and virulence are not well understood. Pseudomonas aeruginosa and Staphylococcus aureus are opportunistic pathogens commonly found together......1 and DK2-P2M24-2003, which comprised several virulence factors and signaling 4-hydroxy-2-alkylquinoline (HAQ) molecules. Strikingly, a further modulation of the HAQ profile was observed in DK2-P2M24-2003 during interaction with S. aureus, resulting in an area with thickened colony morphology...... host-adapted strain, DK2-P2M24-2003, and S. aureus. In this study, characterization by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) imaging mass spectrometry (IMS) and mass spectral (MS) molecular networking revealed a significant metabolic divergence between P. aeruginosa PAO...

Antibiotic resistance profile of Pseudomonas aeruginosa isolated from aquaculture and abattoir environments in urban communities

Directory of Open Access Journals (Sweden)

Isoken Henrietta Igbinosa

2017-01-01

Full Text Available Objective: To characterize multiple antibiotic resistance profile of Pseudomonas aeruginosa from aquaculture and abattoir environments. Methods: Wastewater samples were obtained from the abattoir and aquaculture environments between May 2016 and July 2016 and analysed using standard phenotypic, biochemical and PCR-based methods. Results: The mean pseudomonads count ranged from (4 × 102 ± 1.01 to (2 × 104 ± 0.10 colony-forming unit/mL in the aquaculture environment and (3 × 103 ± 0.00 to (1 × 105 ± 1.00 colony-forming unit/mL in the abattoir environment. A total of 96 isolates of Pseudomonas aeruginosa confirmed by PCR were thereafter selected from both aquaculture and abattoir environments and further characterized for their antimicrobial susceptibility profile by adopting the disc diffusion method. High level of resistance was observed against the aminoglycosides [gentamycin 64/96 (66.67% and kanamycin 52/96 (54.17%], monobactams [aztreonam 76/96 (79.17%], carbapenems [meropenem 52/96 (54.17%], tetracyclines [tetracycline 72/96 (75.00%] and cephems [ceftazidime 72/96 (75.00% and cefuroxime 48/96 (50.00%]. Multiple antibiotic resistant index of the respective isolates ranged from 0.4 to 0.8 while multidrug resistant profile of the isolates revealed that 28 of the respective isolates were resistant to ceftazidime, cefuroxime, gentamycin, kanamycin, aztreonam which belongs to cephems, aminoglycosides and monobactam class of antimicrobials. Conclusions: Findings from the present study therefore underscores the need for effective monitoring of the abattoir and aquaculture environments as they could be the significant source for spreading antibiotic resistant bacteria within the environment.

A novel porcine model of ventilator-associated pneumonia caused by oropharyngeal challenge with Pseudomonas aeruginosa.

Science.gov (United States)

Li Bassi, Gianluigi; Rigol, Montserrat; Marti, Joan-Daniel; Saucedo, Lina; Ranzani, Otavio T; Roca, Ignasi; Cabanas, Maria; Muñoz, Laura; Giunta, Valeria; Luque, Nestor; Rinaudo, Mariano; Esperatti, Mariano; Fernandez-Barat, Laia; Ferrer, Miquel; Vila, Jordi; Ramirez, Jose; Torres, Antoni

2014-05-01

Animal models of ventilator-associated pneumonia (VAP) in primates, sheep, and pigs differ in the underlying pulmonary injury, etiology, bacterial inoculation methods, and time to onset. The most common ovine and porcine models do not reproduce the primary pathogenic mechanism of the disease, through the aspiration of oropharyngeal pathogens, or the most prevalent human etiology. Herein the authors characterize a novel porcine model of VAP due to aspiration of oropharyngeal secretions colonized by Pseudomonas aeruginosa. Ten healthy pigs were intubated, positioned in anti-Trendelenburg, and mechanically ventilated for 72 h. Three animals did not receive bacterial challenge, whereas in seven animals, a P. aeruginosa suspension was instilled into the oropharynx. Tracheal aspirates were cultured and respiratory mechanics were recorded. On autopsy, lobar samples were obtained to corroborate VAP through microbiological and histological studies. In animals not challenged, diverse bacterial colonization of the airways was found and monolobar VAP rarely developed. In animals with P. aeruginosa challenge, colonization of tracheal secretion increased up to 6.39 ± 0.34 log colony-forming unit (cfu)/ml (P VAP was confirmed in six of seven pigs, in 78% of the cases developed in the dependent lung segments (right medium and lower lobes, P = 0.032). The static respiratory system elastance worsened to 41.5 ± 5.8 cm H2O/l (P = 0.001). The authors devised a VAP model caused by aspiration of oropharyngeal P. aeruginosa, a frequent causative pathogen of human VAP. The model also overcomes the practical and legislative limitations associated with the use of primates. The authors' model could be employed to study pathophysiologic mechanisms, as well as novel diagnostic/preventive strategies.

Characterization of clinically isolated thymidine-dependent small-colony variants of Escherichia coli producing extended-spectrum β-lactamase.

Science.gov (United States)

Negishi, Tatsuya; Matsumoto, Takehisa; Horiuchi, Kazuki; Kasuga, Eriko; Natori, Tatsuya; Matsuoka, Mina; Ogiwara, Naoko; Sugano, Mitsutoshi; Uehara, Takeshi; Nagano, Noriyuki; Honda, Takayuki

2018-01-01

Thymidine-dependent small-colony variants (TD-SCVs) are difficult to detect or test for antimicrobial susceptibility. We investigated the characteristics of clonal TD-SCVs of Escherichia coli, both with and without blaCTX-M-3, isolated from a patient. Mutation in the thyA gene was analysed by sequencing, and morphological abnormalities in the colonies and cells of the isolates were examined. Additionally, conjugational transfer experiments were performed to prove the horizontal transferability of plasmids harbouring resistance genes. The TD-SCVs contained a single nucleotide substitution in the thyA gene, c.62G>A, corresponding to p.Arg21His. Morphologically, their colonies were more translucent and flattened than those of the wild-type strain. In addition, cells of the TD-SCVs were swollen and elongated, sometimes with abnormal and incomplete divisions; a large amount of cell debris was also observed. Changing c.62G>A back to the wild-type sequence reversed these abnormalities. Conjugational transfer experiments showed that the TD-SCV of E. coli with blaCTX-M-3 failed to transfer blaCTX-M-3 to E. coli CSH2. However, the TD-SCV of E. coli without blaCTX-M-3 experimentally received the plasmid encoding blaSHV-18 from Klebsiella pneumoniae ATCC 700603 and transferred it to E. coli CSH2. Mutation in the thyA gene causes morphological abnormalities in the colonies and cells of E. coli, as well as inducing thymidine auxotrophy. In addition, TD-SCVs horizontally transmit plasmids encoding resistance genes. It is important to detect TD-SCVs based on their characteristics because they serve as reservoirs of transferable antibiotic resistance plasmids.

RNAi screen reveals an Abl kinase-dependent host cell pathway involved in Pseudomonas aeruginosa internalization.

Directory of Open Access Journals (Sweden)

Julia F Pielage

2008-03-01

Full Text Available Internalization of the pathogenic bacterium Pseudomonas aeruginosa by non-phagocytic cells is promoted by rearrangements of the actin cytoskeleton, but the host pathways usurped by this bacterium are not clearly understood. We used RNAi-mediated gene inactivation of approximately 80 genes known to regulate the actin cytoskeleton in Drosophila S2 cells to identify host molecules essential for entry of P. aeruginosa. This work revealed Abl tyrosine kinase, the adaptor protein Crk, the small GTPases Rac1 and Cdc42, and p21-activated kinase as components of a host signaling pathway that leads to internalization of P. aeruginosa. Using a variety of complementary approaches, we validated the role of this pathway in mammalian cells. Remarkably, ExoS and ExoT, type III secreted toxins of P. aeruginosa, target this pathway by interfering with GTPase function and, in the case of ExoT, by abrogating P. aeruginosa-induced Abl-dependent Crk phosphorylation. Altogether, this work reveals that P. aeruginosa utilizes the Abl pathway for entering host cells and reveals unexpected complexity by which the P. aeruginosa type III secretion system modulates this internalization pathway. Our results furthermore demonstrate the applicability of using RNAi screens to identify host signaling cascades usurped by microbial pathogens that may be potential targets for novel therapies directed against treatment of antibiotic-resistant infections.

Capsule production by Pseudomonas aeruginosa

Energy Technology Data Exchange (ETDEWEB)

Lynn, A.R.

1984-01-01

Mucoid strains of Pseudomonas aeruginosa, associated almost exclusively with chronic respiratory infections in patients with cystic fibrosis, possess a capsule composed of alginic acid similar to one produced by Azotobacter vinelandii. Recent reports have provided evidence that the biosynthetic pathway for alginate in P. aeruginosa may differ from the pathway proposed for A. vinelandii in that synthesis in P. aeruginosa may occur by way of the Entner-Doudoroff pathway. Incorporation of isotope from (6-/sup 14/C)glucose into alginate by both P. aueroginosa and A. vinelandii was 10-fold greater than that from either (1-/sup 14/C)/sup -/ or (2-/sup 14/C)glucose, indicating preferential utilization of the bottom half of the glucose molecule for alginate biosynthesis. These data strongly suggest that the Entner-Doudoroff pathway plays a major role in alginate synthesis in both P. aeruginosa and A. vinelandii. The enzymes of carbohydrate metabolism in mucoid strains of P. aeruginosa appear to be unchanged whether alignate is actively produced or not and activities do not differ significantly from nonmucoid strain PAO.

Protective ventilation reduces Pseudomonas aeruginosa growth in lung tissue in a porcine pneumonia model.

Science.gov (United States)

Sperber, Jesper; Nyberg, Axel; Lipcsey, Miklos; Melhus, Åsa; Larsson, Anders; Sjölin, Jan; Castegren, Markus

2017-08-31

Mechanical ventilation with positive end expiratory pressure and low tidal volume, i.e. protective ventilation, is recommended in patients with acute respiratory distress syndrome. However, the effect of protective ventilation on bacterial growth during early pneumonia in non-injured lungs is not extensively studied. The main objectives were to compare two different ventilator settings on Pseudomonas aeruginosa growth in lung tissue and the development of lung injury. A porcine model of severe pneumonia was used. The protective group (n = 10) had an end expiratory pressure of 10 cm H 2 O and a tidal volume of 6 ml x kg -1 . The control group (n = 10) had an end expiratory pressure of 5 cm H 2 O and a tidal volume of 10 ml x kg -1 . 10 11 colony forming units of Pseudomonas aeruginosa were inoculated intra-tracheally at baseline, after which the experiment continued for 6 h. Two animals from each group received only saline, and served as sham animals. Lung tissue samples from each animal were used for bacterial cultures and wet-to-dry weight ratio measurements. The protective group displayed lower numbers of Pseudomonas aeruginosa (p protective group was unchanged (p protective ventilation with lower tidal volume and higher end expiratory pressure has the potential to reduce the pulmonary bacterial burden and the development of lung injury.

Feeding behaviour of Caenorhabditis elegans is an indicator of Pseudomonas aeruginosa PAO1 virulence

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Shawn Lewenza

2014-08-01

Full Text Available Caenorhabditis elegans is commonly used as an infection model for pathogenesis studies in Pseudomonas aeruginosa. The standard virulence assays rely on the slow and fast killing or paralysis of nematodes but here we developed a behaviour assay to monitor the preferred bacterial food sources of C. elegans. We monitored the food preferences of nematodes fed the wild type PAO1 and mutants in the type III secretion (T3S system, which is a conserved mechanism to inject secreted effectors into the host cell cytosol. A ΔexsEΔpscD mutant defective for type III secretion served as a preferred food source, while an ΔexsE mutant that overexpresses the T3S effectors was avoided. Both food sources were ingested and observed in the gastrointestinal tract. Using the slow killing assay, we showed that the ΔexsEΔpscD had reduced virulence and thus confirmed that preferred food sources are less virulent than the wild type. Next we developed a high throughput feeding behaviour assay with 48 possible food colonies in order to screen a transposon mutant library and identify potential virulence genes. C. elegans identified and consumed preferred food colonies from a grid of 48 choices. The mutants identified as preferred food sources included known virulence genes, as well as novel genes not identified in previous C. elegans infection studies. Slow killing assays were performed and confirmed that several preferred food sources also showed reduced virulence. We propose that C. elegans feeding behaviour can be used as a sensitive indicator of virulence for P. aeruginosa PAO1.

Novel pathways for ameliorating the fitness cost of gentamicin resistant small colony variants

DEFF Research Database (Denmark)

Vestergaard, Martin; Paulander, Wilhelm Erik Axel; Leng, Bingfeng

2016-01-01

Small colony variants (SCVs) of the human pathogen Staphylococcus aureus are associated with persistent infections. Phenotypically, SCVs are characterized by slow growth and they can arise upon interruption of the electron transport chain that consequently reduce membrane potential and thereby...... limit uptake of aminoglycosides (e.g., gentamicin). In this study, we have examined the pathways by which the fitness cost of SCVs can be ameliorated. Five gentamicin resistant SCVs derived from S. aureus JE2 were independently selected on agar plates supplemented with gentamicin. The SCVs carried...... mutations in the menaquinone and hemin biosynthesis pathways, which caused a significant reduction in exponential growth rates relative to wild type (WT; 0.59-0.72) and reduced membrane potentials. Fifty independent lineages of the low-fitness, resistant mutants were serially passaged for up to 500...

Gentamicin in Pseudomonas aeruginosa

African Journals Online (AJOL)

infections by Ps. aeruginosa is contra-indicated. In our study only 2,3 % of the Ps. aeruginosa strains were resistant to gentamicin (MIC 25 Ilg/ml). In view of the synergy reported for combined gentamicin and carbeni- cillin therapy," a combination of these two drugs may be recommended in the treatment of all Pseudomonas.

A yigP mutant strain is a small colony variant of E. coli and shows pleiotropic antibiotic resistance.

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Xia, Hui; Tang, Qiongwei; Song, Jie; Ye, Jiang; Wu, Haizhen; Zhang, Huizhan

2017-12-01

Small colony variants (SCVs) are a commonly observed subpopulation of bacteria that have a small colony size and distinctive biochemical characteristics. SCVs are more resistant than the wild type to some antibiotics and usually cause persistent infections in the clinic. SCV studies have been very active during the past 2 decades, especially Staphylococcus aureus SCVs. However, fewer studies on Escherichia coli SCVs exist, so we studied an E. coli SCV during an experiment involving the deletion of the yigP locus. PCR and DNA sequencing revealed that the SCV was attributable to a defect in the yigP function. Furthermore, we investigated the antibiotic resistance profile of the E. coli SCV and it showed increased erythromycin, kanamycin, and d-cycloserine resistance, but collateral sensitivity to ampicillin, polymyxin, chloramphenicol, tetracycline, rifampin, and nalidixic acid. We tried to determine the association between yigP and the pleiotropic antibiotic resistance of the SCV by analyzing biofilm formation, cellular morphology, and coenzyme Q (Q 8 ) production. Our results indicated that impaired Q 8 biosynthesis was the primary factor that contributed to the increased resistance and collateral sensitivity of the SCV. This study offers a novel genetic basis for E. coli SCVs and an insight into the development of alternative antimicrobial strategies for clinical therapy.

Breeding site selection by colonial waterbirds given various ...

African Journals Online (AJOL)

The number of active colonial waterbird nests at a series of four small constructed wetlands in Cape Town was counted monthly from 1999 to 2008. In total 491 pairs belonging to 11 waterbird species were involved. Between 1997 and 2004 a number of different artificial structures were used to attract colonial waterbirds to ...

Pseudomonas aeruginosa Trent and zinc homeostasis.

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Davies, Corey B; Harrison, Mark D; Huygens, Flavia

2017-09-01

Pseudomonas aeruginosa is a Gram-negative pathogen and the major cause of mortality in patients with cystic fibrosis. The mechanisms that P. aeruginosa strains use to regulate intracellular zinc have an effect on infection, antibiotic resistance and the propensity to form biofilms. However, zinc homeostasis in P. aeruginosa strains of variable infectivity has not been compared. In this study, zinc homeostasis in P. aeruginosa Trent, a highly infectious clinical strain, was compared to that of a laboratory P. aeruginosa strain, ATCC27853. Trent was able to tolerate higher concentrations of additional zinc in rich media than ATCC27853. Further, pre-adaptation to additional zinc enhanced the growth of Trent at non-inhibitory concentrations but the impact of pre-adaption on the growth of ATCC27853 under the same conditions was minimal. The results establish clear differences in zinc-induced responses in Trent and ATCC27853, and how zinc homeostasis can be a promising target for the development of novel antimicrobial strategies for P. aeruginosa infection in cystic fibrosis patients. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Evaluation of combinations of putative anti-biofilm agents and antibiotics to eradicate biofilms of Staphylococcus aureus and Pseudomonas aeruginosa.

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Belfield, Katherine; Bayston, Roger; Hajduk, Nadzieja; Levell, Georgia; Birchall, John P; Daniel, Matija

2017-09-01

To evaluate potential anti-biofilm agents for their ability to enhance the activity of antibiotics for local treatment of localized biofilm infections. Staphylococcus aureus and Pseudomonas aeruginosa in vitro biofilm models were developed. The putative antibiotic enhancers N-acetylcysteine, acetylsalicylic acid, sodium salicylate, recombinant human deoxyribonuclease I, dispersin B, hydrogen peroxide and Johnson's Baby Shampoo (JBS) were tested for their anti-biofilm activity alone and their ability to enhance the activity of antibiotics for 7 or 14 days, against 5 day old biofilms. The antibiotic enhancers were paired with rifampicin and clindamycin against S. aureus and gentamicin and ciprofloxacin against P. aeruginosa. Isolates from biofilms that were not eradicated were tested for antibiotic resistance. Antibiotic levels 10× MIC and 100× MIC significantly reduced biofilm, but did not consistently eradicate it. Antibiotics at 100× MIC with 10% JBS for 14 days was the only treatment to eradicate both staphylococcal and pseudomonal biofilms. Recombinant human deoxyribonuclease I significantly reduced staphylococcal biofilm. Emergence of resistance of surviving isolates was minimal and was often associated with the small colony variant phenotype. JBS enhanced the activity of antibiotics and several other promising anti-biofilm agents were identified. Antibiotics with 10% JBS eradicated biofilms produced by both organisms. Such combinations might be useful in local treatment of localized biofilm infections. © The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Molecular analysis of field strains of Mycoplasma capricolum subspecies capripneumoniae and Mycoplasma mycoides subspecies mycoides, small colony type isolated from goats in Tanzania

DEFF Research Database (Denmark)

Kusiluka, L.J.M.; Ojeniyi, B.; Friis, N.F.

2001-01-01

A molecular analysis of strains of Mycoplasma capricolum subsp, capripneumoniae (M. capripneumoniae) and Mycoplasma mycoides subsp. mycoides, small colony type (M. mycoides SQ isolated from goats was performed using the amplified fragment length polymorphism (AFLP) and pulsed-field gel...

Genetic complexity of fusidic acid-resistant small colony variants (SCV in Staphylococcus aureus.

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Jonas Lannergård

Full Text Available FusE mutants are fusidic acid-resistant small colony variants (SCVs of Staphylococcus aureus that can be selected with aminoglycosides. All FusE SCVs have mutations in rplF, encoding ribosomal protein L6. However, individual FusE mutants including some with the same mutation in rplF display auxotrophy for either hemin or menadione, suggesting that additional mutations are involved. Here we show that FusE SCVs can be divided into three genetic sub-groups and that some carry an additional mutation, in one of the genes required for hemin biosynthesis, or in one of the genes required for menadione biosynthesis. Reversion analysis and genome sequencing support the hypothesis that these combinations of mutations in the rplF, hem, and/or men genes can account for the SCV and auxotrophic phenotypes of FusE mutants.

Expression of antisense small RNAs in response to stress in Pseudomonas aeruginosa

DEFF Research Database (Denmark)

Gómez Lozano, María; Marvig, Rasmus Lykke; Tulstrup, Monica Vera-Lise

2014-01-01

Background: RNA sequencing technologies reveal that bacteria express RNA molecules other than mRNA, rRNA or tRNA. During the last years genome-wide bacterial transcriptomes have been shown to comprise intergenic RNA, antisense RNA, and untranslated regions, all capable of performing diverse...... that the extent of overlap between the studies is very limited. Conclusions: RNA-seq experiments are revealing hundreds of novel transcripts in all bacterial genomes investigated. The comparison between independent studies that used RNA-seq to detect novel asRNAs in P. aeruginosa shows that the overlap between...

Survival, recovery and microcystin release of Microcystis aeruginosa in cold or dark condition

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Ding, Yi; Gan, Nanqin; Liu, Jin; Zheng, Lingling; Li, Lin; Song, Lirong

2017-03-01

Microcystis often dominates phytoplankton in eutrophic lakes and must survive a long period of cold or dark conditions. However, the survival strategies of Microcystis to withstand cold or dark stress are less well known. In this study, we conducted experiments on the responses of two toxic Microcystis aeruginosa strains (FACHB-905 and FACHB-915) and their microcystin release in conditions of low temperature (15°C or 4°C, with illumination) or darkness, and subsequent recovery in standard conditions (25°C with illumination). On exposure to 15°C, a small decrease in cell viability was observed, but the cell number increased gradually, suggesting that M. aeruginosa FACHB-905 and FACHB-915 cells seem in general tolerant in 15°C. Interestingly, our results show that a higher carotenoid content and microcystin release potentially enhance the fitness of surviving cells at 15°C. M. aeruginosa cells exposed to lower temperature light stress (4°C) did not completely lose viability and retained the ability to reinitiate growth. In darkness, the maximum quantum yield ( F v/ F m) and the maximum electron transport rate (ETRmax) values and cell viability of M. aeruginosa cells gradually decreased with time. During the recovery period, the photosynthetic efficiency of M. aeruginosa reverted to the normal level. Additionally, M. aeruginosa FACHB-905 and FACHB-915 exposed to low temperature had increased caspase-3-like activity and DNA fragmentation, which suggests the occurrence of a type of cell death in M. aeruginosa cells under cold stress similar to programmed cell death. Overall, our findings could confer certain advantages on the Microcystis for surviving cold or dark conditions encountered in the annual cycle, and help explain its repeated occurrence in water blooms in large and shallow lakes.

Microbial pathogenesis in cystic fibrosis: co-ordinate regulation of heat-shock response and conversion to mucoidy in Pseudomonas aeruginosa.

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Schurr, M J; Deretic, V

1997-04-01

Conversion of Pseudomonas aeruginosa to the mucoid phenotype plays a major role in the pathogenesis of respiratory infections in cystic fibrosis (CF). One mechanism responsible for mucoidy is based on mutations that inactivate the anti-sigma factor, MucA, which normally inhibits the alternative sigma factor, AIgU. The loss of MucA allows AIgU to freely direct transcription of the genes responsible for the production of the exopolysaccharide alginate resulting in mucoid colony morphology. In Escherichia coli, a close homologue of AIgU, sigma(E), directs transcription of several genes under conditions of extreme heat shock. Here we examined whether AIgU, besides its role in controlling alginate production, affects the heat-shock response in P. aeruginosa. The P. aeruginosa rpoH gene encoding a homologue of the major heat-shock sigma factor, sigma32, was found to be transcribed by AIgU containing RNA polymerase from one of its promoters (P3) identified in this study. Transcription of rpoH from P3 was elevated upon exposure to extreme heat shock in an aIgU-dependent manner. Importantly, the AIgU-dependent promoter of rpoH was found to be activated in mucoid mucA mutants. In keeping with this observation, introduction of a wild-type mucA gene abrogated AIgU-dependent rpoH transcription in mucoid P. aeruginosa laboratory isolates and CF isolates. These results suggest that conversion to mucoidy and the heat-shock response are co-ordinately regulated in P. aeruginosa. The simultaneous activation of both systems in mucA mutants, selected in the lungs of CF patients, may have significance for the inflammatory processes characteristic of the establishment of chronic infection and ensuing clinical deterioration in CF.

Phages can constrain protist predation-driven attenuation of Pseudomonas aeruginosa virulence in multienemy communities

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Friman, Ville-Petri; Buckling, Angus

2014-01-01

The coincidental theory of virulence predicts that bacterial pathogenicity could be a by-product of selection by natural enemies in environmental reservoirs. However, current results are ambiguous and the simultaneous impact of multiple ubiquitous enemies, protists and phages on virulence evolution has not been investigated previously. Here we tested experimentally how Tetrahymena thermophila protist predation and PNM phage parasitism (bacteria-specific virus) alone and together affect the evolution of Pseudomonas aeruginosa PAO1 virulence, measured in wax moth larvae. Protist predation selected for small colony types, both in the absence and presence of phage, which showed decreased edibility to protists, reduced growth in the absence of enemies and attenuated virulence. Although phage selection alone did not affect the bacterial phenotype, it weakened protist-driven antipredatory defence (biofilm formation), its associated pleiotropic growth cost and the correlated reduction in virulence. These results suggest that protist selection can be a strong coincidental driver of attenuated bacterial virulence, and that phages can constrain this effect owing to effects on population dynamics and conflicting selection pressures. Attempting to define causal links such as these might help us to predict the cold and hot spots of coincidental virulence evolution on the basis of microbial community composition of environmental reservoirs. PMID:24671085

Nano-antibiotics in chronic lung infection therapy against Pseudomonas aeruginosa.

Science.gov (United States)

Hadinoto, Kunn; Cheow, Wean Sin

2014-04-01

Antibiotic encapsulation into nanoparticle carriers has emerged as a promising inhaled antibiotic formulation for treatment of chronic Pseudomonas aeruginosa lung infection prevalent in chronic obstructive pulmonary diseases. Attributed to their prolonged lung retention, sustained antibiotic release, and mucus penetrating ability, antibiotic nanoparticles, or nano-antibiotics in short, can address the principal weakness of inhaled antibiotic solution, i.e. low antibiotic exposure in the vicinity of P. aeruginosa biofilm colonies resulting in diminished anti-pseudomonal efficacy after repeated uses. This review details the current state of development and limitations of the two most widely studied forms of nano-antibiotics, i.e. liposomes and polymer nanoparticles. Factors in their formulation that influence the anti-pseudomonal efficacy in vitro and in vivo, such as liposome's membrane rigidity, surface charge, size, and polymer hydrophobicity, are discussed. This review reveals that the superior anti-pseudomonal efficacy of liposomal antibiotics to free antibiotics has been clearly established when they are correctly formulated, with several liposomal antibiotic formulations are currently undergoing clinical trials. Liposomal antibiotics, nevertheless, are not without limitation due to their weak physicochemical stability. In contrast, only mucus penetrating ability of the more stable polymeric nano-antibiotics has been established, while their anti-pseudomonal efficacy has only been examined in vitro from which their superiority to free antibiotics has not been ascertained. Lastly, future research needs to bring liposome and polymer-based nano-antibiotics closer to their clinical realization are identified. Copyright © 2014 Elsevier B.V. All rights reserved.

Morphology offers no clues to asexual vs. sexual origin of small Acropora cervicornis (Scleractinia: Acroporidae colonies

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D. E Williams

2006-12-01

Full Text Available Sexual recruitment of the staghorn coral, Acropora cervicornis, is accepted to be very rare. Instead, these branching corals proliferate through fragmentation leading to dense mono-specific and possibly monoclonal stands. For acroporid corals, which have suffered drastic population declines, dominance of asexual reproduction results in low levels of genotypic diversity and limited ability to re-colonize extirpated areas. Small colonies with a single encrusting, symmetrical base, and few incipient branches are frequently presumed to be the result of a settled planula (i.e. sexual reproduction. Here, we show that colonies fitting this description (i.e., presumed sexual recruits can result from asexual fragmentation. Acropora cervicornis colonies (~20 cm diameter were tagged and observed over eighteen months. In several cases, colony offshoots fused with the adjacent substrate forming secondary disc-like attachment points. Following natural fragmentation, these discs of tissue became separated from the original colony, and were observed to heal and give rise to smaller colonies with striking similarity to the expected morphology of a sexual recruit. Thus, presuming a colony is a sexual recruit based on appearance is unreliable and may lead to inflated expectations of genetic diversity among populations. The accurate assessment of recruitment and genetic diversity is crucial to predicting the recovery potential of these imperiled and ecologically irreplaceable reef corals. Rev. Biol. Trop. 54 (Suppl. 3: 145-151. Epub 2007 Jan. 15.Se ha aceptado que el reclutamiento sexual del coral asta de venado, Acropora cervicornis, es muy raro. Por el contrario, estos corales ramificados proliferan a través de fragmentación, generando densas bases monoespecíficas e incluso monoclonales. Para corales acropóridos, los cuales han sufrido disminuciones de población drásticas, la dominancia de reproducción asexual resulta en bajos niveles de diversidad genot

The absence of a flagellum leads to altered colony morphology, biofilm development and virulence in Vibrio cholerae O139

Science.gov (United States)

Watnick, Paula I.; Lauriano, Crystal M.; Klose, Karl E.; Croal, Laura; Kolter, Roberto

2010-01-01

Summary Throughout most of history, epidemic and pandemic cholera was caused by Vibrio cholerae of the serogroup O1. In 1992, however, a V. cholerae strain of the serogroup O139 emerged as a new agent of epidemic cholera. Interestingly, V. cholerae O139 forms biofilms on abiotic surfaces more rapidly than V. cholerae O1 biotype El Tor, perhaps because regulation of exopolysaccharide synthesis in V. cholerae O139 differs from that in O1 El Tor. Here, we show that all flagellar mutants of V. cholerae O139 have a rugose colony morphology that is dependent on the vps genes. This suggests that the absence of the flagellar structure constitutes a signal to increase exopolysaccharide synthesis. Furthermore, although exopolysaccharide production is required for the development of a three-dimensional biofilm, inappropriate exopolysaccharide production leads to inefficient colonization of the infant mouse intestinal epithelium by flagellar mutants. Thus, precise regulation of exopolysaccharide synthesis is an important factor in the survival of V. cholerae O139 in both aquatic environments and the mammalian intestine. PMID:11136445

Clinical characteristics and outcomes of prosthetic joint infection caused by small colony variant staphylococci.

Science.gov (United States)

Tande, Aaron J; Osmon, Douglas R; Greenwood-Quaintance, Kerryl E; Mabry, Tad M; Hanssen, Arlen D; Patel, Robin

2014-09-30

Small colony variants (SCVs) are naturally occurring subpopulations of bacteria. The clinical characteristics and treatment outcomes of patients with prosthetic joint infection (PJI) caused by staphylococcal SCVs are unknown. This study was a retrospective series of 113 patients with staphylococcal PJI, with prospective testing of archived sonicate fluid samples. SCVs were defined using two-investigator review. Treatment failure was defined as (i) subsequent revision surgery for any reason, (ii) PJI after the index surgery, (iii) prosthesis nonreimplantation due to ongoing infection, or (iv) amputation of the affected limb. There were 38 subjects (34%) with SCVs and 75 (66%) with only normal-phenotype (NP) bacteria. Subjects with SCVs were more likely to have been on chronic antimicrobials prior to surgery (P = 0.048), have had prior surgery for PJI (P = 0.03), have had a longer duration of symptoms (P = 0.0003), and have had a longer time since joint implantation (P = 0.007), compared to those with only NP bacteria. Over a median follow-up of 30.6 months, 9 subjects (24%) with SCVs and 23 (32%) with only NP bacteria experienced treatment failure (P = 0.51). Subjects infected with Staphylococcus aureus were more likely to fail than were those infected with Staphylococcus epidermidis (hazard ratio [HR], 4.03; 95% confidence interval [CI], 1.80 to 9.04). While frequently identified in subjects with PJI and associated with several potential predisposing factors, SCVs were not associated with excess treatment failure compared to NP infections in this study, where they were primarily managed with two-stage arthroplasty exchange. Bacteria with the small colony variant (SCV) phenotype are described in small case series as causing persistent or relapsing infection, but there are insufficient data to suggest that they should be managed differently than infection with normal-phenotype bacteria. In an effort to investigate the clinical importance of this phenotype, we

Colonial Figures: Memories of Street Traders in the Colonial and Early Post-colonial Periods

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Sheri Lynn Gibbings

2012-12-01

Full Text Available This article explores post-colonial memories about street traders among individuals who lived in the former colony of the Dutch East Indies. It argues that these narratives romanticize the relationship between Europeans and indigenous peoples. Street vendors are also used to differentiate between periods within colonial and post-colonial history. The nostalgic representation of interracial contact between Europeans and traders is contrasted with representations of other figures such as the Japanese and the nationalist. A recurring feature of these representations is the ability of Europeans to speak with street traders and imagine what they wanted and needed. The traders are remembered as a social type that transgressed politics and represented the neutrality of the economic sphere as a place for shared communication. The article concludes that the figure of the street vendor contributes to the nostalgic reinvention of the colony but is also used in narratives to differentiate between and mark changes across the colonial and post-colonial periods.

First recorded loss of an emperor penguin colony in the recent period of Antarctic regional warming: implications for other colonies.

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Philip N Trathan

Full Text Available In 1948, a small colony of emperor penguins Aptenodytes forsteri was discovered breeding on Emperor Island (67° 51' 52″ S, 68° 42' 20″ W, in the Dion Islands, close to the West Antarctic Peninsula (Stonehouse 1952. When discovered, the colony comprised approximately 150 breeding pairs; these numbers were maintained until 1970, after which time the colony showed a continuous decline. By 1999 there were fewer than 20 pairs, and in 2009 high-resolution aerial photography revealed no remaining trace of the colony. Here we relate the decline and loss of the Emperor Island colony to a well-documented rise in local mean annual air temperature and coincident decline in seasonal sea ice duration. The loss of this colony provides empirical support for recent studies (Barbraud & Weimerskirch 2001; Jenouvrier et al 2005, 2009; Ainley et al 2010; Barber-Meyer et al 2005 that have highlighted the vulnerability of emperor penguins to changes in sea ice duration and distribution. These studies suggest that continued climate change is likely to impact upon future breeding success and colony viability for this species. Furthermore, a recent circumpolar study by Fretwell & Trathan (2009 highlighted those Antarctic coastal regions where colonies appear most vulnerable to such changes. Here we examine which other colonies might be at risk, discussing various ecological factors, some previously unexplored, that may also contribute to future declines. The implications of this are important for future modelling work and for understanding which colonies actually are most vulnerable.

Staphylococcus aureus small colony variants in diabetic foot infections

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Estrella Cervantes-García

2015-03-01

Full Text Available Background: Staphylococcus aureus (S. aureus is one of the major pathogens causing chronic infections. The ability of S. aureus to acquire resistance to a diverse range of antimicrobial compounds results in limited treatment options, particularly in methicillin-resistant S. aureus (MRSA. A mechanism by which S. aureus develops reduced susceptibility to antimicrobials is through the formation of small colony variants (SCVs. Infections by SCVs of S. aureus are an upcoming problem due to difficulties in laboratory diagnosis and resistance to antimicrobial therapy. Methods: A prospective study was performed on 120 patients diagnosed with both type 2 diabetes mellitus and infected diabetic foot ulcers. The study was carried out from July 2012 to December 2013 in Hospital General de Mexico. The samples were cultured in blood agar, mannitol salt agar, and MacConkey agar media, and incubated at 37°C in aerobic conditions. Results: We describe the first known cases of diabetic foot infections caused by MRSA-SCVs in patients diagnosed with type 2 diabetes mellitus and infected diabetic foot ulcers. In all of our cases, the patients had not received any form of gentamicin therapy. Conclusions: The antibiotic therapy commonly used in diabetic patients with infected diabetic foot ulcers fails in the case of MRSA-SCVs because the intracellular location protects S. aureus-SCVs from the host's defenses and also helps them resist antibiotics. The cases studied in this article add to the spectrum of persistent and relapsing infections attributed to MRSA-SCVs and emphasizes that these variants may also play a relevant role in diabetic foot infections.

Microcystis aeruginosa strengthens the advantage of Daphnia similoides in competition with Moina micrura.

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Tang, Hengxing; Hou, Xinying; Xue, Xiaofeng; Chen, Rui; Zhu, Xuexia; Huang, Yuan; Chen, Yafen

2017-08-31

Microcystis blooms are generally associated with zooplankton shifts by disturbing interspecific relationships. The influence of Microcystis on competitive dominance by different sized zooplanktons showed species-specific dependence. We evaluated the competitive responses of small Moina micrura and large Daphnia similoides to the presence of Microcystis using mixed diets comprising 0%, 20%, and 35% of toxic M. aeruginosa, and the rest of green alga Chlorella pyrenoidosa. No competitive exclusion occurred for the two species under the tested diet combinations. In the absence of M. aeruginosa, the biomasses of the two cladocerans were decreased by the competition between them. However, the Daphnia was less inhibited with the higher biomass, suggesting the competitive dominance of Daphnia. M. aeruginosa treatment suppressed the population growths of the two cladocerans, with the reduced carrying capacities. Nonetheless, the population inhibition of Daphnia by competition was alleviated by the increased Microcystis proportion in diet. As a result, the competitive advantage of Daphnia became more pronounced, as indicated by the higher Daphnia: Moina biomass ratio with increased Microcystis proportions. These results suggested that M. aeruginosa strengthens the advantage of D. similoides in competition with M. micrura, which contributes to the diversified zooplankton shifts observed in fields during cyanobacteria blooms.

Biogeography of late Silurian and devonian rugose corals

Science.gov (United States)

Oliver, W.A.

1977-01-01

Three marine benthic faunal realms can be recognized in the Early and Middle Devonian. The Eastern Americas Realm consisted of most of the eastern half of North America and South America north of the Amazon. This realm extended in a southwest direction from the Devonian equator to approximately 35??S and was an isolated epicontinental sea during much of its history. The Eastern Americas Realm was bounded on the west by the Transcontinental Arch, on the north by the Canadian Shield and on the east and southeast by a peninsular extension of the Old Red Continent. These barriers were emergent during much, but not all, of Devonian time. Seaways beyond these barriers belonged to the Old World Realm. The Malvinokaffric Realm that was farther south was apparently temperate to arctic in climate and latitudinal position and contained few corals. Rugose corals in the Eastern Americas Realm show increasing generic-level endemism from the Late Silurian through the Early Devonian; during the late Early Devonian, 92% of the rugosan genera are not known anywhere else in the world. Endemism decreased through the Middle Devonian to zero in the early Late Devonian. The Early Devonian increase in endemism paralleled, and was probably related to, the development of the Old Red Continent as a barrier between America and Africa-Europe. The waning of endemism in the Middle Devonian reflects the breaching of the land barriers. This permitted some migration in and out of the realm in early Middle Devonian time but greatest movements were in late Middle Devonian time. Principal migration directions were from western or Arctic North America into the Michigan-Hudson Bay area and from the southern Appalachian area into Africa. ?? 1977.

Laser-induced speckle scatter patterns in Bacillus colonies

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Huisung eKim

2014-10-01

Full Text Available Label-free bacterial colony phenotyping technology called BARDOT (BActerial Rapid Detection using Optical scattering Technology provided successful classification of several different bacteria at the genus, species, and serovar level. Recent experiments with colonies of Bacillus species provided strikingly different characteristics of elastic light scatter (ELS patterns, which were comprised of random speckles compared to other bacteria, which are dominated by concentric rings and spokes. Since this laser-based optical sensor interrogates the whole volume of the colony, 3-D information of micro- and macro-structures are all encoded in the far-field scatter patterns. Here, we present a theoretical model explaining the underlying mechanism of the speckle formation by the colonies from Bacillus species. Except for Bacillus polymyxa, all Bacillus spp. produced random bright spots on the imaging plane, which presumably dependent on the cellular and molecular organization and content within the colony. Our scatter model-based analysis revealed that colony spread resulting in variable surface roughness can modify the wavefront of the scatter field. As the center diameter of the Bacillus spp. colony grew from 500 μm to 900 μm, average speckles area decreased 2-fold and the number of small speckles increased 7-fold. In conclusion, as Bacillus colony grows, the average speckle size in the scatter pattern decreases and the number of smaller speckle increases due to the swarming growth characteristics of bacteria within the colony.

Inbred or Outbred? Genetic Diversity in Laboratory Rodent Colonies

Science.gov (United States)

Brekke, Thomas D.; Steele, Katherine A.; Mulley, John F.

2017-01-01

Nonmodel rodents are widely used as subjects for both basic and applied biological research, but the genetic diversity of the study individuals is rarely quantified. University-housed colonies tend to be small and subject to founder effects and genetic drift; so they may be highly inbred or show substantial genetic divergence from other colonies, even those derived from the same source. Disregard for the levels of genetic diversity in an animal colony may result in a failure to replicate results if a different colony is used to repeat an experiment, as different colonies may have fixed alternative variants. Here we use high throughput sequencing to demonstrate genetic divergence in three isolated colonies of Mongolian gerbil (Meriones unguiculatus) even though they were all established recently from the same source. We also show that genetic diversity in allegedly “outbred” colonies of nonmodel rodents (gerbils, hamsters, house mice, deer mice, and rats) varies considerably from nearly no segregating diversity to very high levels of polymorphism. We conclude that genetic divergence in isolated colonies may play an important role in the “replication crisis.” In a more positive light, divergent rodent colonies represent an opportunity to leverage genetically distinct individuals in genetic crossing experiments. In sum, awareness of the genetic diversity of an animal colony is paramount as it allows researchers to properly replicate experiments and also to capitalize on other genetically distinct individuals to explore the genetic basis of a trait. PMID:29242387

A three-phase in-vitro system for studying Pseudomonas aeruginosa adhesion and biofilm formation upon hydrogel contact lenses

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Kohlmann Thomas

2010-11-01

Full Text Available Abstract Background Pseudomonas aeruginosa is commonly associated with contact lens (CL -related eye infections, for which bacterial adhesion and biofilm formation upon hydrogel CLs is a specific risk factor. Whilst P. aeruginosa has been widely used as a model organism for initial biofilm formation on CLs, in-vitro models that closely reproduce in-vivo conditions have rarely been presented. Results In the current investigation, a novel in-vitro biofilm model for studying the adherence of P. aeruginosa to hydrogel CLs was established. Nutritional and interfacial conditions similar to those in the eye of a CL wearer were created through the involvement of a solid:liquid and a solid:air interface, shear forces and a complex artificial tear fluid. Bioburdens varied depending on the CL material and biofilm maturation occurred after 72 h incubation. Whilst a range of biofilm morphologies were visualised including dispersed and adherent bacterial cells, aggregates and colonies embedded in extracellular polymer substances (EPS, EPS fibres, mushroom-like formations, and crystalline structures, a compact and heterogeneous biofilm morphology predominated on all CL materials. Conclusions In order to better understand the process of biofilm formation on CLs and to test the efficacy of CL care solutions, representative in-vitro biofilm models are required. Here, we present a three-phase biofilm model that simulates the environment in the eye of a CL wearer and thus generates biofilms which resemble those commonly observed in-situ.

The Small Colony Variant of Listeria monocytogenes Is More Tolerant to Antibiotics and Has Altered Survival in RAW 264.7 Murine Macrophages

DEFF Research Database (Denmark)

Curtis, Thomas; Gram, Lone; Knudsen, Gitte Maegaard

2016-01-01

Small Colony Variant (SCV) cells of bacteria are a slow-growing phenotype that result from specific defects in the electron transport chain. They form pinpoint colonies on agar plates and have a variety of phenotypic characteristics, such as altered carbon metabolism, decreased toxin and lytic...... monocytogenes (strain SCV E18), similar to the high persister mutant phenotype, survived significantly better than the wild type when exposed over a 48-h period to concentrations above Minimal Inhibitory Concentration for most tested antibiotics. SCV E18 survived more poorly than the wildtype in unactivated RAW......264.7 macrophage cells, presumably because of its reduced listeriolysin O expression, however, it survived better in reactive oxygen species producing, phorbol 12-myristate 13-acetate-activated macrophages. Although SCV E18 was sensitive to oxygen as it entered the stationary phase...

Comparison of efficiency of intravitreal ceftazidime and intravitreal cefepime in the treatment of experimental Pseudomonas aeruginosa endophthalmitis

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Nurettin Deniz

2013-01-01

Full Text Available In this study, we evaluated the efficiency of cefepime in the treatment of experimental Pseudomonas aeruginosa endophthalmitis. We compared the findings with the standard dose of ceftazidime (1 mg/0.1 ml. Thirty-six New-Zealand White rabbits were divided into 6 equal groups and were treated with different methods (Group 1 = sham, Group 2 = 0.5 mg/0.1 ml cefepime, Group 3 = 1 mg/0.1 ml cefepime, Group 4 = 2 mg/0.1 ml cefepime, Group 5 = 1 mg/0.1 ml ceftazidime, Group 6 = control. The eyes of rabbits in each group were examined clinically on 1 st , 3 rd , and 6 th day of the experiment. At 6 th day, 0.1 ml vitreous humor aspirates were obtained and plated for quantification on the blood agar and the results were expressed as colony-forming unit/ml. Subsequently, the eyeballs were enucleated and the histopathological evaluation was performed. Our findings denoted beneficial effects of cefepime in treatment groups (especially, in Groups 3 and 4. Intravitreal cefepime may be an alternative drug in the treatment of P. aeruginosa endophthalmitis.

The Pseudomonas aeruginosa transcriptome in planktonic cultures and static biofilms using RNA sequencing.

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Andreas Dötsch

Full Text Available In this study, we evaluated how gene expression differs in mature Pseudomonas aeruginosa biofilms as opposed to planktonic cells by the use of RNA sequencing technology that gives rise to both quantitative and qualitative information on the transcriptome. Although a large proportion of genes were consistently regulated in both the stationary phase and biofilm cultures as opposed to the late exponential growth phase cultures, the global biofilm gene expression pattern was clearly distinct indicating that biofilms are not just surface attached cells in stationary phase. A large amount of the genes found to be biofilm specific were involved in adaptation to microaerophilic growth conditions, repression of type three secretion and production of extracellular matrix components. Additionally, we found many small RNAs to be differentially regulated most of them similarly in stationary phase cultures and biofilms. A qualitative analysis of the RNA-seq data revealed more than 3000 putative transcriptional start sites (TSS. By the use of rapid amplification of cDNA ends (5'-RACE we confirmed the presence of three different TSS associated with the pqsABCDE operon, two in the promoter of pqsA and one upstream of the second gene, pqsB. Taken together, this study reports the first transcriptome study on P. aeruginosa that employs RNA sequencing technology and provides insights into the quantitative and qualitative transcriptome including the expression of small RNAs in P. aeruginosa biofilms.

Antinociceptive principle from Curcuma aeruginosa

OpenAIRE

Hossain, Chowdhury Faiz; Al-Amin, Mohammad; Sayem, Abu Sadat Md.; Siragee, Ismail Hossain; Tunan, Asif Mahmud; Hassan, Fahima; Kabir, Md. Mohiuddin; Sultana, Gazi Nurun Nahar

2015-01-01

Background The rhizome of Curcuma aeruginosa Roxb (Zingiberaceae) has been used as a traditional folk medicine for the treatment of rheumatic disorders in Bangladesh. The aim of the current study was the bioassay-guided isolation and purification of an antinociceptive principle from the methanol extract of C. aeruginosa rhizomes. Methods The antinociceptive activity was determined using acetic acid induced writhing and formalin induced licking in the Swiss albino mice to investigate central a...

Baicalin inhibits biofilm formation, attenuates the quorum sensing-controlled virulence and enhances Pseudomonas aeruginosa clearance in a mouse peritoneal implant infection model.

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Jing Luo

Full Text Available The quorum sensing (QS circuit plays a role in the precise regulation of genes controlling virulence factors and biofilm formation in Pseudomonas aeruginosa. QS-controlled biofilm formation by Pseudomonas aeruginosa in clinical settings has remained controversial due to emerging drug resistance; therefore, screening diverse compounds for anti-biofilm or anti-QS activities is important. This study demonstrates the ability of sub-minimum inhibitory concentrations (sub-MICs of baicalin, an active natural compound extracted from the traditional Chinese medicinal Scutellaria baicalensis, to inhibit the formation of Pseudomonas aeruginosa biofilms and enhance the bactericidal effects of various conventional antibiotics in vitro. In addition, baicalin exerted dose-dependent inhibitory effects on virulence phenotypes (LasA protease, LasB elastase, pyocyanin, rhamnolipid, motilities and exotoxin A regulated by QS in Pseudomonas aeruginosa. Moreover, the expression levels of QS-regulatory genes, including lasI, lasR, rhlI, rhlR, pqsR and pqsA, were repressed after sub-MIC baicalin treatment, resulting in significant decreases in the QS signaling molecules 3-oxo-C12-HSL and C4-HSL, confirming the ability of baicalin-mediated QS inhibition to alter gene and protein expression. In vivo experiments indicated that baicalin treatment reduces Pseudomonas aeruginosa pathogenicity in Caenorhabditis elegans. Greater worm survival in the baicalin-treated group manifested as an increase in the LT50 from 24 to 96 h. In a mouse peritoneal implant infection model, baicalin treatment enhanced the clearance of Pseudomonas aeruginosa from the implants of mice infected with Pseudomonas aeruginosa compared with the control group. Moreover, the combination of baicalin and antibiotics significantly reduced the numbers of colony-forming units in the implants to a significantly greater degree than antibiotic treatment alone. Pathological and histological analyses revealed

Effects of ginseng on Pseudomonas aeruginosa motility and biofilm formation

DEFF Research Database (Denmark)

Wu, Hong; Lee, Baoleri; Yang, Liang

2011-01-01

protected animal models from developing chronic lung infection by P. aeruginosa. In the present study, the effects of ginseng on the formation of P. aeruginosa biofilms were further investigated in vitro and in vivo. Ginseng aqueous extract at concentrations of 0.5-2.0% did not inhibit the growth of P......Biofilm-associated chronic Pseudomonas aeruginosa lung infections in patients with cystic fibrosis are virtually impossible to eradicate with antibiotics because biofilm-growing bacteria are highly tolerant to antibiotics and host defense mechanisms. Previously, we found that ginseng treatments....... aeruginosa, but significantly prevented P. aeruginosa from forming biofilm. Exposure to 0.5% ginseng aqueous extract for 24 h destroyed most 7-day-old mature biofilms formed by both mucoid and nonmucoid P. aeruginosa strains. Ginseng treatment enhanced swimming and twitching motility, but reduced swarming...

Pseudomonas aeruginosa inhibits the growth of Cryptococcus species.

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Rella, Antonella; Yang, Mo Wei; Gruber, Jordon; Montagna, Maria Teresa; Luberto, Chiara; Zhang, Yong-Mei; Del Poeta, Maurizio

2012-06-01

Pseudomonas aeruginosa is a ubiquitous and opportunistic bacterium that inhibits the growth of different microorganisms, including Gram-positive bacteria and fungi such as Candida spp. and Aspergillus fumigatus. In this study, we investigated the interaction between P. aeruginosa and Cryptococcus spp. We found that P. aeruginosa PA14 and, to a lesser extent, PAO1 significantly inhibited the growth of Cryptococcus spp. The inhibition of growth was observed on solid medium by the visualization of a zone of inhibition of yeast growth and in liquid culture by viable cell counting. Interestingly, such inhibition was only observed when P. aeruginosa and Cryptococcus were co-cultured. Minimal inhibition was observed when cell-cell contact was prevented using a separation membrane, suggesting that cell contact is required for inhibition. Using mutant strains of Pseudomonas quinoline signaling, we showed that P. aeruginosa inhibited the growth of Cryptococcus spp. by producing antifungal molecules pyocyanin, a redox-active phenazine, and 2-heptyl-3,4-dihydroxyquinoline (PQS), an extracellular quorum-sensing signal. Because both P. aeruginosa and Cryptococcus neoformans are commonly found in lung infections of immunocompromised patients, this study may have important implication for the interaction of these microbes in both an ecological and a clinical point of view.

Occurrence of pseudomonas aeruginosa in post-operative wound infection

International Nuclear Information System (INIS)

Oguntibeju, O.O.; Nwobu, R.A.U.

2004-01-01

Objective: To determine the prevalence of Pseudomonas aeruginosa in post-operative wound infection. Results: Out of the 60 bacterial isolates found in post-operative wound infection, 20 (33.3%) were Pseudomonas aeruginosa, followed by Staphylococcus aureus 13(21.7%), Klebsiella species 10(16.7%), Escherichia coli 7(11.7%), Atypical coliform 4(6.7%), Proteus species 4(6.7%), Streptococcus pyogenes 1(1.7%) and Enterococcus faecalis 1(1.7%) in the order. Pseudomonas aeruginosa infections was higher in female than male, ratio 3:2 and was found more among young and elderly debilitated patients. The in vitro sensitivity pattern of 20 isolates of Pseudomonas aeruginosa showed colistin (100%), gentamicin (75%), streptomycin (30%), and tetracycline (10%). Conclusion: The role of Pseudomonas aeruginosa as an agent of nosocomial infection is re-emphasised. (author)

CARBONIFEROUS CORALS AND CHAETETIDS FROM EXOTIC LIMESTONE BLOCK OF THE CRIMEA

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VICTOR OGAR

2015-11-01

Full Text Available A chaetetid sponge and coral fauna from a Carboniferous exotic limestone block in the Lower Jurassic Esciorda olistostrome on the Bodrak River (Crimean Mountains are described for the first time. The Bodrak exotic block is composed of massive limestone. It contains the chaetetid Chaetetes (Boswellia sp., the tabulate coral Multithecopora sp., and poorly preserved rugose corals, including Dibunophyllum? sp., Cordibia? sp. and gen. et sp. indet. Only the fasciculate colonies of the rugose coral Lytvophyllum askynensis (Kossovaya, 2009 are confidently identified. The studied association of fossils is similar to that of the Donets Basin and the Urals and confirms the Lower Bashkirian age of the Bodrak limestone block. 

Phenotypic and molecular characterization of antimicrobial resistance and virulence factors in Pseudomonas aeruginosa clinical isolates from Recife, State of Pernambuco, Brazil

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Paula Regina Luna de Araújo Jácome

2012-12-01

Full Text Available INTRODUCTION: The emergence of carbapenem resistance mechanisms in Pseudomonas aeruginosa has been outstanding due to the wide spectrum of antimicrobial degradation of these bacteria, reducing of therapeutic options. METHODS: Sixty-one clinical strains of P. aeruginosa isolated from five public hospitals in Recife, Pernambuco, Brazil, were examined between 2006 and 2010, aiming of evaluating the profiles of virulence, resistance to antimicrobials, presence of metallo-β-lactamase (MBL genes, and clonal relationship among isolates. RESULTS: A high percentage of virulence factors (34.4% mucoid colonies; 70.5% pyocyanin; 93.4% gelatinase positives; and 72.1% hemolysin positive and a high percentage of antimicrobial resistance rates (4.9% pan-resistant and 54.1% multi-drug resistant isolates were observed. Among the 29 isolates resistant to imipenem and/or ceftazidime, 44.8% (13/29 were MBL producers by phenotypic evaluation, and of these, 46.2% (6/13 were positive for the blaSPM-1 gene. The blaIMP and blaVIM genes were not detected. The molecular typing revealed 21 molecular profiles of which seven were detected in distinct hospitals and periods. Among the six positive blaSPM-1 isolates, three presented the same clonal profile and were from the same hospital, whereas the other three presented different clonal profiles. CONCLUSIONS: These results revealed that P. aeruginosa is able to accumulate different resistance and virulence factors, making the treatment of infections difficult. The identification of blaSPM-1 genes and the dissemination of clones in different hospitals, indicate the need for stricter application of infection control measures in hospitals in Recife, Brazil, aiming at reducing costs and damages caused by P. aeruginosa infections.

Vaccines for preventing infection with Pseudomonas aeruginosa in cystic fibrosis

DEFF Research Database (Denmark)

Johansen, Helle Krogh; Gøtzsche, Peter C

2013-01-01

Chronic pulmonary infection in cystic fibrosis results in progressive lung damage. Once colonisation of the lungs with Pseudomonas aeruginosa occurs, it is almost impossible to eradicate. Vaccines, aimed at reducing infection with Pseudomonas aeruginosa, have been developed.......Chronic pulmonary infection in cystic fibrosis results in progressive lung damage. Once colonisation of the lungs with Pseudomonas aeruginosa occurs, it is almost impossible to eradicate. Vaccines, aimed at reducing infection with Pseudomonas aeruginosa, have been developed....

Reproduction and caste ratios under stress in trematode colonies with a division of labour.

Science.gov (United States)

Lloyd, Melanie M; Poulin, Robert

2013-06-01

Trematodes form clonal colonies in their first intermediate host. Individuals are, depending on species, rediae or sporocysts (which asexually reproduce) and cercariae (which develop within rediae or sporocysts and infect the next host). Some species use a division of labour within colonies, with 2 distinct redial morphs: small rediae (non-reproducing) and large rediae (individuals which produce cercariae). The theory of optimal caste ratio predicts that the ratio of caste members (small to large rediae) responds to environmental variability. This was tested in Philophthalmus sp. colonies exposed to host starvation and competition with the trematode, Maritrema novaezealandensis. Philophthalmus sp. infected snails, with and without M. novaezealandensis, were subjected to food treatments. Reproductive output, number of rediae, and the ratio of small to large rediae were compared among treatments. Philophthalmus sp. colonies responded to host starvation and competition; reproductive output was higher in well-fed snails of both infection types compared with snails in lower food treatments and well-fed, single infected snails compared with well-fed double infected snails. Furthermore, the caste ratio in Philophthalmus sp. colonies was altered in response to competition. This is the first study showing caste ratio responses to environmental pressures in trematodes with a division of labour.

Topography and spatial arrangement of reef-building corals on the fringing reefs of North Jamaica may influence their response to disturbance from bleaching.

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Crabbe, M J C

2010-04-01

Knowledge of factors that are important in reef resilience helps us understand how reefs react following major environmental disturbances such as hurricanes and bleaching. Here we test factors that might have influenced Jamaican reef resilience to, and subsequent recovery from, the 2005 bleaching event, and which might help inform management policy for reefs in the future: reef rugosity and contact of corals with macroalgae. In addition, we test in the field, on Dairy Bull reef, whether aggregated Porites astreoides colonies exhibit enhanced growth when exposed to superior competition from Acopora palmata, as has been found by experiment with the Indo-Pacific corals Porites lobata and the superior competitor Porites rus [Idjadi, J.A., Karlson, R.H., 2007. Spatial arrangement of competitors influences coexistence of reef-building corals. Ecology 88, 2449-2454]. There were significant linear relationships between rugosity and the increase in smallest size classes for Sidastrea siderea, Colpophyllia natans, P. astreoides and Agaricia species, and between rugosity and cover of the branching coral Acropora cervicornis. Linear extension rates of A. cervicornis and radial growth rates of P. astreoides were significantly lower (p6) when in contact with macroalgae. Aggregated colonies of P. astreoides in contact with one another, one of which was in contact with the faster growing competitor A. palmata showed significantly greater growth rates than with just two aggregated P. astreoides colonies alone. These findings suggest that three dimensional topography and complexity is important for reef resilience and viability in the face of environmental stressors such as bleaching. Our findings also support the idea that aggregated spatial arrangements of corals can influence the outcome of interspecific competition and promote species coexistence, important in times of reef recovery after disturbance. Copyright 2009 Elsevier Ltd. All rights reserved.

Complement activation by Pseudomonas aeruginosa biofilms

DEFF Research Database (Denmark)

Jensen, E T; Kharazmi, A; Garred, P

1993-01-01

In chronic infections, such as the bronchopulmonary Pseudomonas aeruginosa infection in cystic fibrosis (CF) patients, bacteria persist despite an intact host immune defense and frequent antibiotic treatment. An important reason for the persistence of the bacteria is their capacity for the biofilm...... mode of growth. In this study we investigated the role of biofilms in activation of complement, a major contributor to the inflammatory process. Complement activation by P. aeruginosa was examined in a complement consumption assay, production of C3 and factor B conversion products assessed by crossed...... immuno-electrophoresis, C5a generation tested by a PMN chemotactic assay, and terminal complement complex formation measured by ELISA. Two of the four assays showed that P. aeruginosa grown in biofilm activated complement less than planktonic bacteria, and all assays showed that activation by intact...

Experimental Pseudomonas aeruginosa mediated rhino sinusitis in mink

DEFF Research Database (Denmark)

Kirkeby, S.; Hammer, A. S.; Høiby, N.

2017-01-01

The nasal and sinus cavities in children may serve as reservoirs for microorganisms that cause recurrent and chronic lung infections. This study evaluates whether the mink can be used as an animal model for studying Pseudomonas aeruginosa mediated rhino-sinusitis since there is no suitable...... in the infected mink shows features of carbohydrate expression comparable to what has been described in the respiratory system after Pseudomonas aeruginosa infection in humans. It is suggested that the mink is suitable for studying Pseudomonas aeruginosa mediated rhino-sinusitis....

Structure analysis of the global metabolic regulator Crc from Pseudomonas aeruginosa.

Science.gov (United States)

Wei, Yong; Zhang, Heng; Gao, Zeng-Qiang; Xu, Jian-Hua; Liu, Quan-Sheng; Dong, Yu-Hui

2013-01-01

The global metabolic regulator catabolite repression control (Crc) has recently been found to modulate the susceptibility to antibiotics and virulence in the opportunistic pathogen Pseudomonas aeruginosa and been suggested as a nonlethal target for novel antimicrobials. In P. aeruginosa, Crc couples with the CA motifs from the small RNA CrcZ to form a post-transcriptional regulator system and is removed from the 5'-end of the target mRNAs. In this study, we first reported the crystal structure of Crc from P. aeruginosa refined to 2.20 Å. The structure showed that it consists of two halves with similar overall topology and there are 11 β strands surrounded by 13 helices, forming a four-layered α/β-sandwich. The circular dichroism spectroscopy revealed that it is thermostable in solution and shares similar characteristics to that in crystal. Comprehensive structural analysis and comparison with the homologies of Crc showed high similarity with several known nucleases and consequently may be classified into a member exodeoxyribonuclease III. However, it shows distinct substrate specificity (RNA as the preferred substrate) compared to these DNA endonucleases. Structural comparisons also revealed potential RNA recognition and binding region mainly consisting of five flexible loops. Our structure study provided the basis for the future application of Crc as a target to develop new antibiotics. Copyright © 2012 International Union of Biochemistry and Molecular Biology, Inc.

Current therapies for pseudomonas aeruginosa.

Science.gov (United States)

Giamarellou, Helen; Kanellakopoulou, Kyriaki

2008-04-01

Based on the worldwide prevalence of multidrug-resistant strains of Pseudomas aeruginosa and the fact that no newer antipseudomonal agents are available, this article aims to investigate therapeutic solutions for combating infections caused by P aeruginosa, including multidrug-resistant strains. The article focuses mainly on colistin, the re-emerging old antibiotic that possesses prominent antipseudomonal activity in vitro and on doripenem, a newer carbapenem that seems to be close to its global marketing. Regarding older antipseudomonal antibiotics that have been reviewed extensively, only newer aspects on their use are considered in this article.

Iridovirus and microsporidian linked to honey bee colony decline.

Science.gov (United States)

Bromenshenk, Jerry J; Henderson, Colin B; Wick, Charles H; Stanford, Michael F; Zulich, Alan W; Jabbour, Rabih E; Deshpande, Samir V; McCubbin, Patrick E; Seccomb, Robert A; Welch, Phillip M; Williams, Trevor; Firth, David R; Skowronski, Evan; Lehmann, Margaret M; Bilimoria, Shan L; Gress, Joanna; Wanner, Kevin W; Cramer, Robert A

2010-10-06

In 2010 Colony Collapse Disorder (CCD), again devastated honey bee colonies in the USA, indicating that the problem is neither diminishing nor has it been resolved. Many CCD investigations, using sensitive genome-based methods, have found small RNA bee viruses and the microsporidia, Nosema apis and N. ceranae in healthy and collapsing colonies alike with no single pathogen firmly linked to honey bee losses. We used Mass spectrometry-based proteomics (MSP) to identify and quantify thousands of proteins from healthy and collapsing bee colonies. MSP revealed two unreported RNA viruses in North American honey bees, Varroa destructor-1 virus and Kakugo virus, and identified an invertebrate iridescent virus (IIV) (Iridoviridae) associated with CCD colonies. Prevalence of IIV significantly discriminated among strong, failing, and collapsed colonies. In addition, bees in failing colonies contained not only IIV, but also Nosema. Co-occurrence of these microbes consistently marked CCD in (1) bees from commercial apiaries sampled across the U.S. in 2006-2007, (2) bees sequentially sampled as the disorder progressed in an observation hive colony in 2008, and (3) bees from a recurrence of CCD in Florida in 2009. The pathogen pairing was not observed in samples from colonies with no history of CCD, namely bees from Australia and a large, non-migratory beekeeping business in Montana. Laboratory cage trials with a strain of IIV type 6 and Nosema ceranae confirmed that co-infection with these two pathogens was more lethal to bees than either pathogen alone. These findings implicate co-infection by IIV and Nosema with honey bee colony decline, giving credence to older research pointing to IIV, interacting with Nosema and mites, as probable cause of bee losses in the USA, Europe, and Asia. We next need to characterize the IIV and Nosema that we detected and develop management practices to reduce honey bee losses.

5-Aminolevulinic acid induced photodynamic inactivation on Staphylococcus aureus and Pseudomonas aeruginosa

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Chien-Ming Hsieh

2014-09-01

Full Text Available The aim of the present study was to develop a simple and fast screening technique to directly evaluate the bactericidal effects of 5-aminolevulinic acid (ALA-mediated photodynamic inactivation (PDI and to determine the optimal antibacterial conditions of ALA concentrations and the total dosage of light in vitro. The effects of PDI on Staphylococcus aureus and Pseudomonas aeruginosa in the presence of various concentrations of ALA (1.0 mM, 2.5 mM, 5.0 mM, 10.0 mM were examined. All bacterial strains were exponentially grown in the culture medium at room temperature in the dark for 60 minutes and subsequently irradiated with 630 ± 5 nm using a light-emitting diode (LED red light device for accumulating the light doses up to 216 J/cm2. Both bacterial species were susceptible to the ALA-induced PDI. Photosensitization using 1.0 mM ALA with 162 J/cm2 light dose was able to completely reduce the viable counts of S. aureus. A significant decrease in the bacterial viabilities was observed for P. aeruginosa, where 5.0 mM ALA was photosensitized by accumulating the light dose of 162 J/cm2. We demonstrated that the use of microplate-based assays—by measuring the apparent optical density of bacterial colonies at 595 nm—was able to provide a simple and reliable approach for quickly choosing the parameters of ALA-mediated PDI in the cell suspensions.

5-Aminolevulinic acid induced photodynamic inactivation on Staphylococcus aureus and Pseudomonas aeruginosa.

Science.gov (United States)

Hsieh, Chien-Ming; Huang, Yen-Hao; Chen, Chueh-Pin; Hsieh, Bo-Chuan; Tsai, Tsuimin

2014-09-01

The aim of the present study was to develop a simple and fast screening technique to directly evaluate the bactericidal effects of 5-aminolevulinic acid (ALA)-mediated photodynamic inactivation (PDI) and to determine the optimal antibacterial conditions of ALA concentrations and the total dosage of light in vitro. The effects of PDI on Staphylococcus aureus and Pseudomonas aeruginosa in the presence of various concentrations of ALA (1.0 mM, 2.5 mM, 5.0 mM, 10.0 mM) were examined. All bacterial strains were exponentially grown in the culture medium at room temperature in the dark for 60 minutes and subsequently irradiated with 630 ± 5 nm using a light-emitting diode (LED) red light device for accumulating the light doses up to 216 J/cm 2 . Both bacterial species were susceptible to the ALA-induced PDI. Photosensitization using 1.0 mM ALA with 162 J/cm 2 light dose was able to completely reduce the viable counts of S. aureus. A significant decrease in the bacterial viabilities was observed for P. aeruginosa, where 5.0 mM ALA was photosensitized by accumulating the light dose of 162 J/cm 2 . We demonstrated that the use of microplate-based assays-by measuring the apparent optical density of bacterial colonies at 595 nm-was able to provide a simple and reliable approach for quickly choosing the parameters of ALA-mediated PDI in the cell suspensions. Copyright © 2013. Published by Elsevier B.V.

Understanding Long-Run African Growth : Colonial Institutions or Colonial Education?

NARCIS (Netherlands)

Bolt, J.; Bezemer, D.J.

2009-01-01

Long-term growth in developing countries has been explained in four frameworks: 'extractive colonial institutions' (Acemoglu et al., 2001), 'colonial legal origin' (La Porta et al., 2004), 'geography' (Gallup et al., 1998) and 'colonial human capital' (Glaeser et al., 2004). In this paper we test

Pseudomonas aeruginosa Population Structure Revisited

Science.gov (United States)

Pirnay, Jean-Paul; Bilocq, Florence; Pot, Bruno; Cornelis, Pierre; Zizi, Martin; Van Eldere, Johan; Deschaght, Pieter; Vaneechoutte, Mario; Jennes, Serge; Pitt, Tyrone; De Vos, Daniel

2009-01-01

At present there are strong indications that Pseudomonas aeruginosa exhibits an epidemic population structure; clinical isolates are indistinguishable from environmental isolates, and they do not exhibit a specific (disease) habitat selection. However, some important issues, such as the worldwide emergence of highly transmissible P. aeruginosa clones among cystic fibrosis (CF) patients and the spread and persistence of multidrug resistant (MDR) strains in hospital wards with high antibiotic pressure, remain contentious. To further investigate the population structure of P. aeruginosa, eight parameters were analyzed and combined for 328 unrelated isolates, collected over the last 125 years from 69 localities in 30 countries on five continents, from diverse clinical (human and animal) and environmental habitats. The analysed parameters were: i) O serotype, ii) Fluorescent Amplified-Fragment Length Polymorphism (FALFP) pattern, nucleotide sequences of outer membrane protein genes, iii) oprI, iv) oprL, v) oprD, vi) pyoverdine receptor gene profile (fpvA type and fpvB prevalence), and prevalence of vii) exoenzyme genes exoS and exoU and viii) group I pilin glycosyltransferase gene tfpO. These traits were combined and analysed using biological data analysis software and visualized in the form of a minimum spanning tree (MST). We revealed a network of relationships between all analyzed parameters and non-congruence between experiments. At the same time we observed several conserved clones, characterized by an almost identical data set. These observations confirm the nonclonal epidemic population structure of P. aeruginosa, a superficially clonal structure with frequent recombinations, in which occasionally highly successful epidemic clones arise. One of these clones is the renown and widespread MDR serotype O12 clone. On the other hand, we found no evidence for a widespread CF transmissible clone. All but one of the 43 analysed CF strains belonged to a ubiquitous P

Pseudomonas aeruginosa Dose-Response and Bathing Water Infection

Science.gov (United States)

Pseudomonas aeruginosa is the most commonly identified opportunistic pathogen associated with pool acquired bather disease. To better understand why this microorganism poses this protracted problem we recently appraised P. aeruginosa pool risk management. Much is known about the ...

Pseudomonas aeruginosa diversity in distinct paediatric patient groups

DEFF Research Database (Denmark)

Tramper-Stranders, G.A.; Ent, C.K. van der; Wolfs, T.F.

2008-01-01

the other groups. A group of clonal isolates was observed among patients from the CF-chronic and CF-1 groups. These or different clonal isolates were not encountered among the three other patient groups. No characteristic resistance pattern could be identified among isolates from the distinct patient groups......Pseudomonas aeruginosa is a pathogen that often infects patients who are either immunocompromised or have local defects in host defences. It is known that cystic fibrosis (CF) patients are sometimes infected with certain clonal isolates. It is not clear whether these clonal isolates also infect non......-CF patients and whether clonality of isolates occurs in other patient groups. The aim of this study was to investigate P. aeruginosa diversity and the occurrence of clones within five distinct paediatric patient groups susceptible to P. aeruginosa infection. P. aeruginosa isolates were cultured from 157...

Acquisition and Role of Molybdate in Pseudomonas aeruginosa

Science.gov (United States)

Pederick, Victoria G.; Eijkelkamp, Bart A.; Ween, Miranda P.; Begg, Stephanie L.; Paton, James C.

2014-01-01

In microaerophilic or anaerobic environments, Pseudomonas aeruginosa utilizes nitrate reduction for energy production, a process dependent on the availability of the oxyanionic form of molybdenum, molybdate (MoO42−). Here, we show that molybdate acquisition in P. aeruginosa occurs via a high-affinity ATP-binding cassette permease (ModABC). ModA is a cluster D-III solute binding protein capable of interacting with molybdate or tungstate oxyanions. Deletion of the modA gene reduces cellular molybdate concentrations and results in inhibition of anaerobic growth and nitrate reduction. Further, we show that conditions that permit nitrate reduction also cause inhibition of biofilm formation and an alteration in fatty acid composition of P. aeruginosa. Collectively, these data highlight the importance of molybdate for anaerobic growth of P. aeruginosa and reveal novel consequences of nitrate reduction on biofilm formation and cell membrane composition. PMID:25172858

Secretory IgA as a diagnostic tool for Pseudomonas aeruginosa respiratory colonization

DEFF Research Database (Denmark)

Aanaes, Kasper; Johansen, Helle Krogh; Poulsen, Steen Seier

2012-01-01

BACKGROUND: Pseudomonas aeruginosa sinusitis may be the focus for intermittent lung colonization in patients with cystic fibrosis (CF). The sinusitis may induce elevated IgA levels in nasal secretion and saliva against P. aeruginosa. METHODS: 120 CF patients chronically infected, intermittently...... colonized or without P. aeruginosa in the lungs participated in this cross-sectional study. IgA and IgG against P. aeruginosa sonicate and alginate were measured in nasal secretions, saliva, and in serum by ELISA. RESULTS: The intermittently colonized patients had significantly higher IgA levels in nasal...... secretions and saliva than those without P. aeruginosa in the lungs, indicating that P. aeruginosa sinusitis may precede intermittent colonization and chronic infection of the lungs. CONCLUSIONS: Specific IgA against P. aeruginosa in nasal secretions and saliva can contribute to differentiation between...

Faster activation of polymorphonuclear neutrophils in resistant mice during early innate response to Pseudomonas aeruginosa lung infection

DEFF Research Database (Denmark)

Jensen, Peter Østrup; Moser, C; Kobayashi, O

2004-01-01

challenge with alginate embedded P. aeruginosa. These parameters were correlated with the quantitative bacteriology and histopathology of the lungs. After challenge, the content of granulocyte colony-stimulating factor (G-CSF) and macrophage inflammatory protein-2 (MIP-2) was increased in the lungs...... and the sera and the percentage of PMNs was increased in the blood. However, 2 days after challenge the concentration of G-CSF and MIP-2 was higher in the lungs and sera of BALB/c mice. CD11b expression was higher on the PMNs of the C3H/HeN mice. The expression of CD62L on PMNs of both strains of mice...... and the persistent chemotactic gradient provided by MIP-2 in the lungs....

Spectrophotometric, colorimetric and visually detection of Pseudomonas aeruginosa ETA gene based gold nanoparticles DNA probe and endonuclease enzyme

Science.gov (United States)

Amini, Bahram; Kamali, Mehdi; Salouti, Mojtaba; Yaghmaei, Parichehreh

2018-06-01

Colorimetric DNA detection is preferred over other methods for clinical molecular diagnosis because it does not require expensive equipment. In the present study, the colorimetric method based on gold nanoparticles (GNPs) and endonuclease enzyme was used for the detection of P. aeruginosa ETA gene. Firstly, the primers and probe for P. aeruginosa exotoxin A (ETA) gene were designed and checked for specificity by the PCR method. Then, GNPs were synthesized using the citrate reduction method and conjugated with the prepared probe to develop the new nano-biosensor. Next, the extracted target DNA of the bacteria was added to GNP-probe complex to check its efficacy for P. aeruginosa ETA gene diagnosis. A decrease in absorbance was seen when GNP-probe-target DNA cleaved into the small fragments of BamHI endonuclease due to the weakened electrostatic interaction between GNPs and the shortened DNA. The right shift of the absorbance peak from 530 to 562 nm occurred after adding the endonuclease. It was measured using a UV-VIS absorption spectroscopy that indicates the existence of the P. aeruginosa ETA gene. Sensitivity was determined in the presence of different concentrations of target DNA of P. aeruginosa. The results obtained from the optimized conditions showed that the absorbance value has linear correlation with concentration of target DNA (R: 0.9850) in the range of 10-50 ng mL-1 with the limit detection of 9.899 ng mL-1. Thus, the specificity of the new method for detection of P. aeruginosa was established in comparison with other bacteria. Additionally, the designed assay was quantitatively applied to detect the P. aeruginosa ETA gene from 103 to 108 CFU mL-1 in real samples with a detection limit of 320 CFU mL-1.

Novel Targets for Treatment of Pseudomonas aeruginosa Biofilms

DEFF Research Database (Denmark)

Alhede, Morten; Alhede, Maria; Bjarnsholt, Thomas

2014-01-01

Pseudomonas aeruginosa causes infection in all parts of the human body. The bacterium is naturally resistant to a wide range of antibiotics. In addition to resistance mechanisms such as efflux pumps, the ability to form aggregates, known as biofilm, further reduces Pseudomonas aeruginosa...

Prevalence and analysis of Pseudomonas aeruginosa in chinchillas

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Aoyama Naoki

2010-11-01

Full Text Available Abstract Background Chinchillas (Chinchilla laniger are popular as pets and are often used as laboratory animals for various studies. Pseudomonas aeruginosa is a major infectious agent that causes otitis media, pneumonia, septicaemia enteritis, and sudden death in chinchillas. This bacterium is also a leading cause of nosocomial infections in humans. To prevent propagation of P. aeruginosa infection among humans and animals, detailed characteristics of the isolates, including antibiotic susceptibility and genetic features, are needed. In this study, we surveyed P. aeruginosa distribution in chinchillas bred as pets or laboratory animals. We also characterized the isolates from these chinchillas by testing for antibiotic susceptibility and by gene analysis. Results P. aeruginosa was isolated from 41.8% of the 67 chinchillas included in the study. Slide agglutination and pulsed-field gel electrophoresis discriminated 5 serotypes and 7 unique patterns, respectively. For the antibiotic susceptibility test, 40.9% of isolates were susceptible to gentamicin, 77.3% to ciprofloxacin, 77.3% to imipenem, and 72.7% to ceftazidime. DNA analyses confirmed that none of the isolates contained the gene encoding extended-spectrum β-lactamases; however, 2 of the total 23 isolates were found to have a gene similar to the pilL gene that has been identified in the pathogenicity island of a clinical isolate of P. aeruginosa. Conclusions P. aeruginosa is widely spread in chinchillas, including strains with reduced susceptibility to the antibiotics and highly virulent strains. The periodic monitoring should be performed to help prevent the propagation of this pathogen and reduce the risk of infection from chinchillas to humans.

Pseudomonas aeruginosa burn wound infection in a dedicated ...

African Journals Online (AJOL)

Background. Pseudomonas aeruginosa infection is a major cause of morbidity in burns patients. There is a paucity of publications dealing with this infection in the paediatric population. We describe the incidence, microbiology and impact of P. aeruginosa infection in a dedicated paediatric burns unit. Methods.

Effects of protozoan grazing on colony formation in Phaeocystis globosa (Prymnesiophyceae) and the potential costs and benefits

DEFF Research Database (Denmark)

Jakobsen, Hans Henrik; Tang, K.W.

2002-01-01

. scintillans increased the mean colony size by up to 50 % relative to the controls, whereas grazing by G. dominans enhanced the mean colony size by up to 3-fold. Microscopic observations confirmed that N. scintillans was also able to ingest small colonies. In contrast, G. dominans apparently did not ingest...

Genetic diversity affects colony survivorship in commercial honey bee colonies

Science.gov (United States)

Tarpy, David R.; vanEngelsdorp, Dennis; Pettis, Jeffrey S.

2013-08-01

Honey bee ( Apis mellifera) queens mate with unusually high numbers of males (average of approximately 12 drones), although there is much variation among queens. One main consequence of such extreme polyandry is an increased diversity of worker genotypes within a colony, which has been shown empirically to confer significant adaptive advantages that result in higher colony productivity and survival. Moreover, honey bees are the primary insect pollinators used in modern commercial production agriculture, and their populations have been in decline worldwide. Here, we compare the mating frequencies of queens, and therefore, intracolony genetic diversity, in three commercial beekeeping operations to determine how they correlate with various measures of colony health and productivity, particularly the likelihood of queen supersedure and colony survival in functional, intensively managed beehives. We found the average effective paternity frequency ( m e ) of this population of honey bee queens to be 13.6 ± 6.76, which was not significantly different between colonies that superseded their queen and those that did not. However, colonies that were less genetically diverse (headed by queens with m e ≤ 7.0) were 2.86 times more likely to die by the end of the study when compared to colonies that were more genetically diverse (headed by queens with m e > 7.0). The stark contrast in colony survival based on increased genetic diversity suggests that there are important tangible benefits of increased queen mating number in managed honey bees, although the exact mechanism(s) that govern these benefits have not been fully elucidated.

An improved method for staining cell colonies in clonogenic assays.

Science.gov (United States)

Guda, Kishore; Natale, Leanna; Markowitz, Sanford D

2007-06-01

Clonogenic assay is a widely used experimental approach to test for the effects of drugs/genes on the growth and proliferative characteristics of cells in vitro. Accurate quantitation of treatment effects in clonogeneic assays depends on the ability to visualize and count cell colonies precisely. We report a novel method (referred as ETeB) for staining cell colonies grown on plastic and specially coated substrates like collagen. Using colon cancer cell lines grown on plastic and collagen, we compared the colony staining efficiencies of the widely used methylene blue, and Ethidium bromide (ETeB) stains. Results show that the ETeB protocol works well on plastic and is extremely effective for staining colonies on collagen when compared to methylene blue. The key features and advantages of ETeB technique are; (a) reduction in background for colonies grown on collagen and possibly other substrates, (b) the whole procedure takes less than a minute, (c) no post-stain washing step is required which eliminates colony losses for cell lines that are loosely adherent, (d) colony visualization and counting can be done immediately following the staining procedure using a standard UV illuminator and software, and (e) the method works across a wide variety of cell lines. The simplicity and robustness of this procedure should warrant its usage in both small and large-scale clonogenic experiments.

Cost and time-effective method for multi-scale measures of rugosity, fractal dimension, and vector dispersion from coral reef 3D models.

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G C Young

Full Text Available We present a method to construct and analyse 3D models of underwater scenes using a single cost-effective camera on a standard laptop with (a free or low-cost software, (b no computer programming ability, and (c minimal man hours for both filming and analysis. This study focuses on four key structural complexity metrics: point-to-point distances, linear rugosity (R, fractal dimension (D, and vector dispersion (1/k. We present the first assessment of accuracy and precision of structure-from-motion (SfM 3D models from an uncalibrated GoPro™ camera at a small scale (4 m2 and show that they can provide meaningful, ecologically relevant results. Models had root mean square errors of 1.48 cm in X-Y and 1.35 in Z, and accuracies of 86.8% (R, 99.6% (D at scales 30-60 cm, 93.6% (D at scales 1-5 cm, and 86.9 (1/k. Values of R were compared to in-situ chain-and-tape measurements, while values of D and 1/k were compared with ground truths from 3D printed objects modelled underwater. All metrics varied less than 3% between independently rendered models. We thereby improve and rigorously validate a tool for ecologists to non-invasively quantify coral reef structural complexity with a variety of multi-scale metrics.

Ap-PCR typing of carbapenem sensitive Pseudomonas aeruginosa ...

African Journals Online (AJOL)

In this study the antibiotic susceptibility of 51 P. aeruginosa strains isolated from clinical samples were detected by the disc diffusion test. The susceptibility of P. aeruginosa strains were found as respectively 55% amicacin, 43% aztreonam, 75% netilmycin, 68% sefepim, 73% ceftazidim, 76% ciproflaxacin, 37% gentamicin, ...

Synergistic Interaction Between Phage Therapy and Antibiotics Clears Pseudomonas Aeruginosa Infection in Endocarditis and Reduces Virulence.

Science.gov (United States)

Oechslin, Frank; Piccardi, Philippe; Mancini, Stefano; Gabard, Jérôme; Moreillon, Philippe; Entenza, José M; Resch, Gregory; Que, Yok-Ai

2017-03-01

Increasing antibiotic resistance warrants therapeutic alternatives. Here we investigated the efficacy of bacteriophage-therapy (phage) alone or combined with antibiotics against experimental endocarditis (EE) due to Pseudomonas aeruginosa, an archetype of difficult-to-treat infection. In vitro fibrin clots and rats with aortic EE were treated with an antipseudomonas phage cocktail alone or combined with ciprofloxacin. Phage pharmacology, therapeutic efficacy, and resistance were determined. In vitro, single-dose phage therapy killed 7 log colony-forming units (CFUs)/g of fibrin clots in 6 hours. Phage-resistant mutants regrew after 24 hours but were prevented by combination with ciprofloxacin (2.5 × minimum inhibitory concentration). In vivo, single-dose phage therapy killed 2.5 log CFUs/g of vegetations in 6 hours (P 6 log CFUs/g of vegetations in 6 hours and successfully treating 64% (n = 7/11) of rats. Phage-resistant mutants emerged in vitro but not in vivo, most likely because resistant mutations affected bacterial surface determinants important for infectivity (eg, the pilT and galU genes involved in pilus motility and LPS formation). Single-dose phage therapy was active against P. aeruginosa EE and highly synergistic with ciprofloxacin. Phage-resistant mutants had impaired infectivity. Phage-therapy alone or combined with antibiotics merits further clinical consideration. © The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America.

On colonial grounds

NARCIS (Netherlands)

Dommelen, Peter Alexander René van

1998-01-01

As a study of the colonial situations of first millennium BC Sardinia, this book is as much an investigation into colonialism as a sociological category, as it explores the specific historical conditions of a particular region. Taking a fresh look at colonialism in Mediterranean archaeology from a

A Carbenicillin R Factor from Pseudomonas aeruginosa | van ...

African Journals Online (AJOL)

Of 64 carbenicillin-resistant Pseudomonas aeruginosa strains 40 transferred this resistance to Escherichia coli. R factor RP-638 isolated from Ps. aeruginosa strain 638 conferred resistance to ampicillin, carbenicillin, kanamycin, neomycin and tetracycline. This R factor was transferred at frequencies 01 10-7 to 10-4 between ...

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

International Nuclear Information System (INIS)

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

2016-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

Huang, Xiaolong [State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072 (China); Wuhan Zhongke Hydrobiological Environment Engineering Co., Ltd, Wuhan 430071 (China); Tu, Yenan; Song, Chaofeng; Li, Tiancui; Lin, Juan [State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072 (China); Graduate University of the Chinese Academy of Sciences, Beijing 100049 (China); Wu, Yonghong [State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Sciences, Chinese Academy of Sciences, Nanjing 210008 (China); Liu, Jiantong [State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072 (China); Wu, Chenxi, E-mail: chenxi.wu@ihb.ac.cn [State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072 (China)

2016-03-15

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

Carbapenem Susceptibility and Multidrug-Resistance in Pseudomonas aeruginosa Isolates in Egypt.

Science.gov (United States)

Hashem, Hany; Hanora, Amro; Abdalla, Salah; Shawky, Alaa; Saad, Alaa

2016-11-01

Resistant Pseudomonas aeruginosa is a serious concern for antimicrobial therapy, as the common isolates exhibit variable grades of resistance, involving beta-lactamase enzymes, beside native defense mechanisms. The present study was designed to determine the occurrence of Metallo-β- Lactamases (MBL) and Amp C harboring P. aeruginosa isolates from Suez Canal university hospital in Ismailia, Egypt. A total of 147 P. aeruginosa isolates, recovered from 311 patients during a 10-month period, were collected between May 2013 and February 2014; the isolates were collected from urine, wound and sputum. Minimum inhibitory concentration (MIC) determined by agar dilution methods was ≥2 μg/mL for meropenem and imipenem. Identification of P. aeruginosa was confirmed using API 20NE. Metallo-β- Lactamases and Amp C were detected based on different phenotypic methods. Overall, 26.5% of P. aeruginosa isolates (39/147) were carbapenem resistant isolates. Furthermore, 64.1% (25/39) were MBL producers, these isolates were screened by the combined disc and disc diffusion methods to determine the ability of MBL production. Both MBL and Amp C harbored P. aeruginosa isolates were 28% (7/25). Sixty-four percent of P. aeruginosa isolates were multidrug resistant (MDR) (16/25). The sensitivity toward polymyxin, imipenem, norfloxacin, piperacillin-tazobactam and gentamicin was 99%, 91%, 88%, 82% and 78%, respectively. The resistance rate towards cefotaxime, ceftazidime, cefepime, aztreonam and meropenem was 98.6%, 86%, 71.4%, 34% and 30%, respectively. Multidrug resistance was significantly associated with MBL production in P. aeruginosa . Early detection of MBL-producing P. aeruginosa and hospital antibiotic policy prescription helps proper antimicrobial therapy and avoidance of dissemination of these multidrug resistance isolates.

Predation of artificial ground nests on white-tailed prairie dog colonies

Science.gov (United States)

Baker, B.W.; Stanley, T.R.; Sedgwick, J.A.

1999-01-01

Prairie dog (Cynomys spp.) colonies are unique to prairie and shrub-steppe landscapes. However, widespread eradication, habitat loss, and sylvatic plague (Yersinia pestis) have reduced their numbers by 98% since historical times. Birds associated with prairie dogs also are declining. Potential nest predators, such as coyotes (Canis latrans), swift foxes (Vulpes velox), and badgers (Taxidea taxus), may be attracted to colonies where a high concentration of prairie dogs serve as available prey. Increased abundance of small mammals, including prairie dogs, also may increase the risk of predation for birds nesting on colonies. Finally, because grazing by prairie dogs may decrease vegetation height and canopy cover, bird nests may be easier for predators to locate. In this study, we placed 1,444 artificial ground nests on and off 74 white-tailed prairie dog (C. leucurus) colonies to test the hypothesis that nest predation rates are higher on colonies than at nearby off sites (i.e., uncolonized habitat). We sampled colonies from 27 May to 16 July 1997 at the following 3 complexes: Coyote Basin, Utah and Colorado; Moxa Arch, Wyoming; and Shirley Basin, Wyoming. Differences in daily predation rates between colonies and paired off sites averaged 1.0% (P = 0.060). When converted to a typical 14-day incubation period, predation rates averaged 14% higher on colonies (57.7 ?? 2.7%; ?? ?? SE) than at off sites (50.4 ?? 3.1%). Comparisons of habitat variables on colonies to off sites showed percent canopy cover of vegetation was similar (P = 0.114), percent bare ground was higher on colonies (P 0.288). Although we found the risk of nest predation was higher on white-tailed prairie dog colonies than at off sites, fitness of birds nesting on colonies might depend on other factors that influence foraging success, reproductive success, or nestling survival.

Disinfection of Pseudomonas aeruginosa biofilm contaminated tube lumens with ultraviolet C light emitting diodes

DEFF Research Database (Denmark)

Bak, Jimmy; Ladefoged, Søren D; Tvede, Michael

2010-01-01

with biofilm was investigated. It was shown that UVC light propagation was possible through both Teflon and catheter tubes (silicone). The disinfection efficiency of the diodes was demonstrated on tubes contaminated artificially with a Pseudomonas aeruginosa biofilm. The tubes were connected to a flow system...... and biofilms were produced during a 3 day period. Tubes in lengths of 10 (Teflon, silicone) and 20 cm (Teflon) were contaminated. Tubes for control and for UVC treatment were contaminated in parallel. Biofilms were sampled from the total inner surface of the tubes. Colony counts on the control samples were...... in the range of 5 x 10(5)-1.3 x 10(9) CFU ml(-1), with disinfection rates in the range 96-100%. The applied UVC doses corresponded to treatment times between 15 and 300 min. Disinfection (100%) was obtained in 10 cm Teflon tubes exposed for 30 min (detection limit...

Disinfection of Pseudomonas aeruginosa biofilm contaminated tube lumens with ultraviolet C light emitting diodes

DEFF Research Database (Denmark)

Bak, Jimmy; Ladefoged, S.D.; Tvede, M.

2010-01-01

with biofilm was investigated. It was shown that UVC light propagation was possible through both Teflon and catheter tubes ( silicone). The disinfection efficiency of the diodes was demonstrated on tubes contaminated artificially with a Pseudomonas aeruginosa biofilm. The tubes were connected to a flow system...... and biofilms were produced during a 3 day period. Tubes in lengths of 10 ( Teflon, silicone) and 20 cm ( Teflon) were contaminated. Tubes for control and for UVC treatment were contaminated in parallel. Biofilms were sampled from the total inner surface of the tubes. Colony counts on the control samples were...... in the range of 5 x 10(5)-1.3 x 10(9) CFU ml(-1), with disinfection rates in the range 96-100%. The applied UVC doses corresponded to treatment times between 15 and 300 min. Disinfection (100%) was obtained in 10 cm Teflon tubes exposed for 30 min (detection limit...

Bacteriophage Infectivity Against Pseudomonas aeruginosa in Saline Conditions

KAUST Repository

Scarascia, Giantommaso

2018-05-02

Pseudomonas aeruginosa is a ubiquitous member of marine biofilm, and reduces thiosulfate to produce toxic hydrogen sulfide gas. In this study, lytic bacteriophages were isolated and applied to inhibit the growth of P. aeruginosa in planktonic mode at different temperature, pH, and salinity. Bacteriophages showed optimal infectivity at a multiplicity of infection of 10 in saline conditions, and demonstrated lytic abilities over all tested temperature (25, 30, 37, and 45°C) and pH 6–9. Planktonic P. aeruginosa exhibited significantly longer lag phase and lower specific growth rates upon exposure to bacteriophages. Bacteriophages were subsequently applied to P. aeruginosa-enriched biofilm and were determined to lower the relative abundance of Pseudomonas-related taxa from 0.17 to 5.58% in controls to 0.01–0.61% in treated microbial communities. The relative abundance of Alphaproteobacteria, Pseudoalteromonas, and Planococcaceae decreased, possibly due to the phage-induced disruption of the biofilm matrix. Lastly, when applied to mitigate biofouling of ultrafiltration membranes, bacteriophages were determined to reduce the transmembrane pressure increase by 18% when utilized alone, and by 49% when used in combination with citric acid. The combined treatment was more effective compared with the citric acid treatment alone, which reported ca. 30% transmembrane pressure reduction. Collectively, the findings demonstrated that bacteriophages can be used as a biocidal agent to mitigate undesirable P. aeruginosa-associated problems in seawater applications.

Discovery of an inhibitor of the production of the Pseudomonas aeruginosa virulence factor pyocyanin in wild-type cells

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Bernardas Morkunas

2016-07-01

Full Text Available Pyocyanin is a small molecule produced by Pseudomonas aeruginosa that plays a crucial role in the pathogenesis of infections by this notorious opportunistic pathogen. The inhibition of pyocyanin production has been identified as an attractive antivirulence strategy for the treatment of P. aeruginosa infections. Herein, we report the discovery of an inhibitor of pyocyanin production in cultures of wild-type P. aeruginosa which is based around a 4-alkylquinolin-2(1H-one scaffold. To the best of our knowledge, this is the first reported example of pyocyanin inhibition by a compound based around this molecular framework. The compound may therefore be representative of a new structural sub-class of pyocyanin inhibitors, which could potentially be exploited in in a therapeutic context for the development of critically needed new antipseudomonal agents. In this context, the use of wild-type cells in this study is notable, since the data obtained are of direct relevance to native situations. The compound could also be of value in better elucidating the role of pyocyanin in P. aeruginosa infections. Evidence suggests that the active compound reduces the level of pyocyanin production by inhibiting the cell–cell signalling mechanism known as quorum sensing. This could have interesting implications; quorum sensing regulates a range of additional elements associated with the pathogenicity of P. aeruginosa and there is a wide range of other potential applications where the inhibition of quorum sensing is desirable.

Why Does the Healthy Cornea Resist Pseudomonas aeruginosa Infection?

Science.gov (United States)

Evans, David J.; Fleiszig, Suzanne M. J.

2013-01-01

Purpose To provide our perspective on why the cornea is resistant to infection based on our research results with Pseudomonas aeruginosa. Perspective We focus on our current understanding of the interplay between bacteria, tear fluid and the corneal epithelium that determine health as the usual outcome, and propose a theoretical model for how contact lens wear might change those interactions to enable susceptibility to P. aeruginosa infection. Methods Use of “null-infection” in vivo models, cultured human corneal epithelial cells, contact lens-wearing animal models, and bacterial genetics help to elucidate mechanisms by which P. aeruginosa survive at the ocular surface, adheres, and traverses multilayered corneal epithelia. These models also help elucidate the molecular mechanisms of corneal epithelial innate defense. Results and Discussion Tear fluid and the corneal epithelium combine to make a formidable defense against P. aeruginosa infection of the cornea. Part of that defense involves the expression of antimicrobials such as β-defensins, the cathelicidin LL-37, cytokeratin-derived antimicrobial peptides, and RNase7. Immunomodulators such as SP-D and ST2 also contribute. Innate defenses of the cornea depend in part on MyD88, a key adaptor protein of TLR and IL-1R signaling, but the basal lamina represents the final barrier to bacterial penetration. Overcoming these defenses involves P. aeruginosa adaptation, expression of the type three secretion system, proteases, and P. aeruginosa biofilm formation on contact lenses. Conclusion After more than two decades of research focused on understanding how contact lens wear predisposes to P. aeruginosa infection, our working hypothesis places blame for microbial keratitis on bacterial adaptation to ocular surface defenses, combined with changes to the biochemistry of the corneal surface caused by trapping bacteria and tear fluid against the cornea under the lens. PMID:23601656

Staphylococcus aureus small colony variants are resistant to the antimicrobial peptide lactoferricin B.

Science.gov (United States)

Samuelsen, Orjan; Haukland, Hanne Husom; Kahl, Barbara C; von Eiff, Christof; Proctor, Richard A; Ulvatne, Hilde; Sandvik, Kjersti; Vorland, Lars H

2005-12-01

To determine whether Staphylococcus aureus small colony variants (SCVs) are resistant to the antimicrobial peptide lactoferricin B. To assess if deficiency in transmembrane potential, a common characteristic of SCVs that are haemin- or menadione-auxotrophs, affects the uptake of the peptide into the bacterial cytoplasm. A broth microdilution technique was used for susceptibility testing to determine the MIC of lactoferricin B for SCVs with three different auxotrophisms (haemin, menadione or thymidine) and their isogenic parent strains. Both clinical isolates and genetically defined mutants were used. The internalization of lactoferricin B in a hemB mutant and the respective parent strain was studied using transmission electron microscopy and immunogold labelling. All SCVs showed reduced susceptibility to lactoferricin B irrespective of their auxotrophy compared with their isogenic parent strains. The MIC for all SCVs was >256 mg/L, whereas the MICs for the parent strains ranged from 16-256 mg/L. Surprisingly, the hemB mutant contained significantly more lactoferricin B intracellularly than the respective parent strain. The resistance mechanism of SCVs towards the antimicrobial peptide lactoferricin B is presumably caused by the metabolic changes present in SCVs rather than by a changed transmembrane potential of SCVs or reduced uptake of the peptide.

Chromosomally Encoded mcr-5 in Colistin non-susceptible Pseudomonas aeruginosa.

Science.gov (United States)

Snesrud, Erik; Maybank, Rosslyn; Kwak, Yoon I; Jones, Anthony R; Hinkle, Mary K; Mc Gann, Patrick

2018-05-29

Whole genome sequencing (WGS) of historical Pseudomonas aeruginosa clinical isolates identified a chromosomal copy of mcr-5 within a Tn 3 -like transposon in P. aeruginosa MRSN 12280. The isolate was non-susceptible to colistin by broth microdilution and genome analysis revealed no mutations known to confer colistin resistance. To the best of our knowledge, this is the first report of mcr in colistin non-susceptible P. aeruginosa .

Ireland – a test case of Post-colonialism / Post colonialism

Directory of Open Access Journals (Sweden)

Brenda Murray

2006-05-01

Full Text Available Contextualisation This review attempts to set the stage for post-colonial theorising, in the light of alternative representations of ‘whiteness’, on issues of gender, race and language within the discourse of equality. In this paper Ireland and the Irish provide a backdrop against which the nature and impact of colonialism on the colonised and the coloniser are explored. Many challenging questions emerge about the ideological basis of post colonial theory, not least when traditional paradigms of racism, as conveyed by the black / white dichotomy, are examined: Ireland presents a context, it is argued, where subjugation is of white on white. Linked to this is the language of the coloniser, a powerful hegemonic force which, in some situations, has been nurtured by the colonised and later developed into a text which is unique, producing a new literature which, it is asserted, truly invokes the ‘post colonial’. Abstract: Post-colonialism – essentially a critique of colonialism, is characterised by a process of disengagement from the colonial epoch and has taken many forms. In this article a set of phenomena are examined that have become inscribed in the cultures of the colonised with a view to identifying alternative cultural origins and dispositions recovered in this post-colonial era. Ireland and the Irish provide the background context of this exploration into perspectives generated by the peripheral or post-colonial nations. Globalisation, too, has had a role to play in the increasing de-territorialisation of communities as a result of cross-frontier mobility, increased intra-community mobility and new communication technologies. A critical reflection on the process of disengagement leads the author to conclude that we must come to recognise new cultural forms which are accepting of a heterogeneous and inclusive society: one which is not characterised by difference.

Detection of Pseudomonas aeruginosa in sputum headspace through volatile organic compound analysis

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Goeminne Pieter C

2012-10-01

Full Text Available Abstract Introduction Chronic pulmonary infection is the hallmark of Cystic Fibrosis lung disease. Searching for faster and easier screening may lead to faster diagnosis and treatment of Pseudomonas aeruginosa (P. aeruginosa. Our aim was to analyze and build a model to predict the presence of P. aeruginosa in sputa. Methods Sputa from 28 bronchiectatic patients were used for bacterial culturing and analysis of volatile compounds by gas chromatography–mass spectrometry. Data analysis and model building were done by Partial Least Squares Regression Discriminant analysis (PLS-DA. Two analysis were performed: one comparing P. aeruginosa positive with negative cultures at study visit (PA model and one comparing chronic colonization according to the Leeds criteria with P. aeruginosa negative patients (PACC model. Results The PA model prediction of P. aeruginosa presence was rather poor, with a high number of false positives and false negatives. On the other hand, the PACC model was stable and explained chronic P. aeruginosa presence for 95% with 4 PLS-DA factors, with a sensitivity of 100%, a positive predictive value of 86% and a negative predictive value of 100%. Conclusion Our study shows the potential for building a prediction model for the presence of chronic P. aeruginosa based on volatiles from sputum.

Evaluation of a FRET-peptide substrate to predict virulence in Pseudomonas aeruginosa.

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Wendy E Kaman

Full Text Available Pseudomonas aeruginosa produces a number of proteases that are associated with virulence and disease progression. A substrate able to detect P. aeruginosa-specific proteolytic activity could help to rapidly alert clinicians to the virulence potential of individual P. aeruginosa strains. For this purpose we designed a set of P. aeruginosa-specific fluorogenic substrates, comprising fluorescence resonance energy transfer (FRET-labeled peptides, and evaluated their applicability to P. aeruginosa virulence in a range of clinical isolates. A FRET-peptide comprising three glycines (3xGly was found to be specific for the detection of P. aeruginosa proteases. Further screening of 97 P. aeruginosa clinical isolates showed a wide variation in 3xGly cleavage activity. The absence of 3xGly degradation by a lasI knock out strain indicated that 3xGly cleavage by P. aeruginosa could be quorum sensing (QS-related, a hypothesis strengthened by the observation of a strong correlation between 3xGly cleavage, LasA staphylolytic activity and pyocyanin production. Additionally, isolates able to cleave 3xGly were more susceptible to the QS inhibiting antibiotic azithromycin (AZM. In conclusion, we designed and evaluated a 3xGly substrate possibly useful as a simple tool to predict virulence and AZM susceptibility.

Effects of Iron on DNA Release and Biofilm Development by Pseudomonas Aeruginosa

DEFF Research Database (Denmark)

Yang, Liang; Barken, Kim Bundvig; Skindersø, Mette Elena

2007-01-01

Extracellular DNA is one of the major matrix components in Pseudomonas aeruginosa biofilms. It functions as an intercellular connector and plays a role in stabilization of the biofilms. Evidence that DNA release in P. aeruginosa PAO1 biofilms is controlled by the las-rhl and pqs quorum-sensing sy......Extracellular DNA is one of the major matrix components in Pseudomonas aeruginosa biofilms. It functions as an intercellular connector and plays a role in stabilization of the biofilms. Evidence that DNA release in P. aeruginosa PAO1 biofilms is controlled by the las-rhl and pqs quorum......-sensing systems has been previously presented. This paper provides evidence that DNA release in P. aeruginosa PAO1 biofilms is also under iron regulation. Experiments involving cultivation of P. aeruginosa in microtitre trays suggested that pqs expression, DNA release and biofilm formation were favoured in media...

Aspergillus triggers phenazine production in Pseudomonas aeruginosa

DEFF Research Database (Denmark)

Jensen, Britt Guillaume; Jelsbak, Lars; Søndergaard, Ib

in the contact area of A. niger, A. flavus, A. oryzae, but not A. fumigatus. In addition, other metabolites with UV chromophores similar to the phenazines were only found in the contact zone between Aspergillus and Pseudomonas. No change in secondary metabolite profiles were seen for the Aspergilli, when......Objectives: Pseudomonas aeruginosa is an opportunistic human pathogen, commonly infecting cystic fibrosis (CF) patients. Aspergilli, especially Aspergillus fumigatus, are also frequently isolated from CF patients. Our aim was to examine the possible interaction between P. aeruginosa and different...... Aspergillus species. Methods: A suspension of fungal spores was streaked onto WATM agar plates. After 24 hours incubation at 37 °C, a P. aeruginosa overnight culture was streaked out perpendicular to the fungal streak. The plates were incubated at 37 °C for five days, examined and plugs were extracted...

Pseudomonas aeruginosa AlgR Phosphorylation Status Differentially Regulates Pyocyanin and Pyoverdine Production

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Alexander S. Little

2018-01-01

Full Text Available Pseudomonas aeruginosa employs numerous, complex regulatory elements to control expression of its many virulence systems. The P. aeruginosa AlgZR two-component regulatory system controls the expression of several crucial virulence phenotypes. We recently determined, through transcriptomic profiling of a PAO1 ΔalgR mutant strain compared to wild-type PAO1, that algZR and hemCD are cotranscribed and show differential iron-dependent gene expression. Previous expression profiling was performed in strains without algR and revealed that AlgR acts as either an activator or repressor, depending on the gene. Thus, examination of P. aeruginosa gene expression from cells locked into different AlgR phosphorylation states reveals greater physiological relevance. Therefore, gene expression from strains carrying algR alleles encoding a phosphomimetic (AlgR D54E or a phosphoablative (AlgR D54N form were compared by microarray to PAO1. Transcriptome analyses of these strains revealed 25 differentially expressed genes associated with iron siderophore biosynthesis or heme acquisition or production. The PAO1 algR D54N mutant produced lower levels of pyoverdine but increased expression of the small RNAs prrf1 and prrf2 compared to PAO1. In contrast, the algR D54N mutant produced more pyocyanin than wild-type PAO1. On the other hand, the PAO1 algR D54E mutant produced higher levels of pyoverdine, likely due to increased expression of an iron-regulated gene encoding the sigma factor pvdS, but it had decreased pyocyanin production. AlgR specifically bound to the prrf2 and pvdS promoters in vitro. AlgR-dependent pyoverdine production was additionally influenced by carbon source rather than the extracellular iron concentration per se. AlgR phosphorylation effects were also examined in a Drosophila melanogaster feeding, murine acute pneumonia, and punch wound infection models. Abrogation of AlgR phosphorylation attenuated P. aeruginosa virulence in these infection

Serotyping and analysis of produced pigments kinds by Pseudomonas aeruginosa clinical isolates

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Stanković-Nedeljković Nataša

2011-01-01

Full Text Available Background/Aim. Pseudomonas aeruginosa (P. aeruginosa is devided into 20 serotypes on the base of the International Antigenic Typing Scheme. P. aeruginosa serotyping is important because of few reasons but epidemiological is the most important. The aim of the study was serotyping of P. aeruginosa clinical isolates, analysing of single clinical isolates P. aeruginosa present in the particular samples, and analysing of pyocianin and fluorescin production in different isolates of P. aeruginosa. Methods. A total of 223 isolates of P. aeruginosa, isolated in the microbiological laboratory of the Health Center “Aleksinac”, Aleksinac, were examinated. P. aeruginosa isolates were put on the pseudomonas isolation agar, pseudomonas agar base, acetamid agar, asparagin prolin broth, pseudomonas asparagin broth, Bushnnell-Haas agar, cetrimid agar base, King A and King B plates, plates for pyocianin production, plates for fluorescin production and tripticasa soya agar (Himedia. Polyvalent and monovalent serums were used in the agglutination (Biorad. Pigment production was analysed on the bases of growth on the plates for pyocianin and fluorescin production. Results. Serologically, we identificated the serovars as follows: O1, O3, O4, O5, O6, O7, O8, O10, O11 and O12. O1 (38% was the most often serovar, then O11 (19% and O6 (8.6%. A total of 18.6% (42 isolates did not agglutinate with any serum, whereas 21 isolates agglutinated only with polyvalent serum. The majority of P. aeruginosa isolates produced fluorescin, 129 (58.54%, 53 (22.94% produced pyocianin whereas 49 (21.21% isolates produced both pigments. Conclusion. P. aeruginosa was isolated most of the from urine, sputum and other materials. The majority often serovars were O1, O6 and O11. The most of isolates produced fluorescin (58.54%, while 22.94% producted pyocianin and 21.21% both pigments.

[Risk factors for Pseudomonas aeruginosa infections, resistant to carbapenem].

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Ghibu, Laura; Miftode, Egidia; Teodor, Andra; Bejan, Codrina; Dorobăţ, Carmen Mihaela

2010-01-01

Since their introduction in clinical practice,carbapenems have been among the most powerful antibiotics for treating serious infections cased by Gram-negative nosocomial pathogens, including Pseudomonas aeruginosa. The emergence of betalactamases with carbapenem-hydrolyzing activity is of major clinical concern. Pseudomonas aeruginosa is a leading cause of nosocomial infection. Risk factors for colonization with carbapenems-resistant Pseudomonas in hospital are: history of P. aeruginosa infection or colonization within the previous year, (length of hospital stay, being bedridden or in the ICU, mechanical ventilation, malignant disease, and history of chronic obstructive pulmonary disease have all been identified as independent risk factors for MDR P. aeruginosa infection. Long-term-care facilities are also reservoirs of resistant bacteria. Risk factors for colonization of LTCF residents with resistant bacteria included age > 86 years, antibiotic treatment in the previous 3 months, indwelling devices, chronic obstructive pulmonary disease, physical disability, and the particular LTCF unit.

Vaccines for preventing infection with Pseudomonas aeruginosa in cystic fibrosis

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Johansen, H.K.; Gøtzsche, Peter C.; Johansen, Helle Krogh

2008-01-01

BACKGROUND: Chronic pulmonary infection in cystic fibrosis results in progressive lung damage. Once colonisation of the lungs with Pseudomonas aeruginosa occurs, it is almost impossible to eradicate. Vaccines, aimed at reducing infection with Pseudomonas aeruginosa, have been developed. OBJECTIVES......: To assess the effectiveness of vaccination against Pseudomonas aeruginosa in cystic fibrosis. SEARCH STRATEGY: We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register using the terms vaccines AND pseudomonas (last search May 2008) and PubMed using the terms vaccin* AND cystic...... fibrosis (last search May 2008). SELECTION CRITERIA: Randomised trials (published or unpublished) comparing Pseudomonas aeruginosa vaccines (oral, parenteral or intranasal) with control vaccines or no intervention in cystic fibrosis. DATA COLLECTION AND ANALYSIS: The authors independently selected trials...

Vaccines for preventing infection with Pseudomonas aeruginosa in cystic fibrosis

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Johansen, Helle Krogh; Gøtzsche, Peter C

2015-01-01

BACKGROUND: Chronic pulmonary infection in cystic fibrosis results in progressive lung damage. Once colonisation of the lungs with Pseudomonas aeruginosa occurs, it is almost impossible to eradicate. Vaccines, aimed at reducing infection with Pseudomonas aeruginosa, have been developed....... This is an update of a previously published review. OBJECTIVES: To assess the effectiveness of vaccination against Pseudomonas aeruginosa in cystic fibrosis. SEARCH METHODS: We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register using the terms vaccines AND pseudomonas (last search 30...... March 2015). We previously searched PubMed using the terms vaccin* AND cystic fibrosis (last search 30 May 2013). SELECTION CRITERIA: Randomised trials (published or unpublished) comparing Pseudomonas aeruginosa vaccines (oral, parenteral or intranasal) with control vaccines or no intervention in cystic...

Respiratory syncytial virus infection facilitates acute colonization of Pseudomonas aeruginosa in mice

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de Vrankrijker, Angélica M M; Wolfs, Tom F W; Ciofu, Oana

2009-01-01

virus infections in facilitating colonization and infection with P. aeruginosa. A study was undertaken to determine whether respiratory syncytial virus (RSV) infection could facilitate the initiation of an acute infection with P. aeruginosa in vivo. Balb/c mice were infected intranasally with P......Pseudomonas aeruginosa causes opportunistic infections in immunocompromised individuals and patients ventilated mechanically and is the major pathogen in patients with cystic fibrosis, in which it causes chronic infections. Epidemiological, in vitro and animal data suggest a role for respiratory....... These results suggest that RSV can facilitate the initiation of acute P. aeruginosa infection without the RSV infection being clinically apparent. This could have implications for treatment strategies to prevent opportunistic P. aeruginosa lung infection....

Pseudomonas aeruginosa uses T3SS to inhibit diabetic wound healing.

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Goldufsky, Josef; Wood, Stephen J; Jayaraman, Vijayakumar; Majdobeh, Omar; Chen, Lin; Qin, Shanshan; Zhang, Chunxiang; DiPietro, Luisa A; Shafikhani, Sasha H

2015-01-01

Diabetic foot ulcers are responsible for more hospitalizations than any other complication of diabetes. Bacterial infection is recognized as an important factor associated with impaired healing in diabetic ulcers. Pseudomonas aeruginosa is the most frequently detected Gram-negative pathogen in diabetic ulcers. P. aeruginosa infection has been shown to impair healing in diabetic wounds in a manner that correlates with its ability to form biofilm. While the majority of infections in diabetic ulcers are biofilm associated, 33% of infections are nonbiofilm in nature. P. aeruginosa is the most prevalent Gram-negative pathogen in all diabetic wound types, which suggests that the deleterious impact of P. aeruginosa on healing in diabetic wounds goes beyond its ability to form biofilm and likely involves other factors. The Type III Secretion System (T3SS) virulence structure is required for the pathogenesis of all P. aeruginosa clinical isolates, suggesting that it may also play a role in the inhibition of wound repair in diabetic skin ulcers. We evaluated the role of T3SS in mediating P. aeruginosa-induced tissue damage in the wounds of diabetic mice. Our data demonstrate that P. aeruginosa establishes a robust and persistent infection in diabetic wounds independent of its ability to form biofilm and causes severe wound damage in a manner that primarily depends on its T3SS. © 2015 by the Wound Healing Society.

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

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

2007-06-01

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

Pseudomonas aeruginosa disrupts Caenorhabditis elegans iron homeostasis, causing a hypoxic response and death.

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Kirienko, Natalia V; Kirienko, Daniel R; Larkins-Ford, Jonah; Wählby, Carolina; Ruvkun, Gary; Ausubel, Frederick M

2013-04-17

The opportunistic pathogen Pseudomonas aeruginosa causes serious human infections, but effective treatments and the mechanisms mediating pathogenesis remain elusive. Caenorhabditis elegans shares innate immune pathways with humans, making it invaluable to investigate infection. To determine how P. aeruginosa disrupts host biology, we studied how P. aeruginosa kills C. elegans in a liquid-based pathogenesis model. We found that P. aeruginosa-mediated killing does not require quorum-sensing pathways or host colonization. A chemical genetic screen revealed that iron chelators alleviate P. aeruginosa-mediated killing. Consistent with a role for iron in P. aeruginosa pathogenesis, the bacterial siderophore pyoverdin was required for virulence and was sufficient to induce a hypoxic response and death in the absence of bacteria. Loss of the C. elegans hypoxia-inducing factor HIF-1, which regulates iron homeostasis, exacerbated P. aeruginosa pathogenesis, further linking hypoxia and killing. As pyoverdin is indispensable for virulence in mice, pyoverdin-mediated hypoxia is likely to be relevant in human pathogenesis. Copyright © 2013 Elsevier Inc. All rights reserved.

The periplasmic protein TolB as a potential drug target in Pseudomonas aeruginosa.

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Alessandra Lo Sciuto

Full Text Available The Gram-negative bacterium Pseudomonas aeruginosa is one of the most dreaded pathogens in the hospital setting, and represents a prototype of multi-drug resistant "superbug" for which effective therapeutic options are very limited. The identification and characterization of new cellular functions that are essential for P. aeruginosa viability and/or virulence could drive the development of anti-Pseudomonas compounds with novel mechanisms of action. In this study we investigated whether TolB, the periplasmic component of the Tol-Pal trans-envelope protein complex of Gram-negative bacteria, represents a potential drug target in P. aeruginosa. By combining conditional mutagenesis with the analysis of specific pathogenicity-related phenotypes, we demonstrated that TolB is essential for P. aeruginosa growth, both in laboratory and clinical strains, and that TolB-depleted P. aeruginosa cells are strongly defective in cell-envelope integrity, resistance to human serum and several antibiotics, as well as in the ability to cause infection and persist in an insect model of P. aeruginosa infection. The essentiality of TolB for P. aeruginosa growth, resistance and pathogenicity highlights the potential of TolB as a novel molecular target for anti-P. aeruginosa drug discovery.

SENSITIVITY TO ANTIBIOTICS, ANTISEPTICAL NOSOCOMIAL PSEUDOMONAS AERUGINOSA, ISOLATED IN UROLOGICAL PATIENTS

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Rymsha E.V.

2015-05-01

cultures around the disks with antibiotics. To explore sensitivity to antiseptics used commercial samples drug Decesan® (decamethoxin of 0.02% solution ("YURI-PHARM", Ukraine, Miramistin® 0.01% solution (benzyldimethyl-myristoylation- Propylamine chloride monohydrate (ZAO Pharmaceutical firm "Darnitsa" and Chlorhexidine (chlorhexidine digluconate 0.05% solution (PJSC "Monfarm". Comparative evaluation of sensitivity of microorganisms to the test preparations was determined by the minimum bactericidal concentration (MBsC standard method, serial dilutions of the drug in a liquid medium (μg⁄ml. Results and discussion. Just received 20 nosocomially strains of P. аeruginosa. Isolated strains had the typical morphology polymorphic thin sticks, gramnegative on dense nutrient media formed a rounded, translucent colonies with a smooth edge, with a blue-green pigment. The biochemical properties referenceusa gram-negative bacteria were determined using Neverlast-24 (PLIVA – Lachema a. s. Brno, Czech Republic. The results of the determination of antibiotics susceptibility of tested strains P. aeruginosa. The greatest activity against the studied strains of P. аeruginosa had Meropenem, amikacin, ceftazidime and imipenem. Nimensa frequency of resistant strains identified to Meropenem were insensitive to 10% of strains of P. aeruginosa. From resistant to Meropenem 6 strains had perekhresne resistance to imipenem. The second activity with β-lactam antibiotics were identified ceftazidime. Insensitive to it were 5%. Antoniniani penicillins were less active than the carbapenems and ceftazidime.So resistant to Pirillo/tazobactam were 30% of the isolates. The most frequent combinations of stability were gentamicin – piperacillin 55,3%, gentamicin – piperacillin – piperacillin/tazobactam 35%. One strain of P. aeruginosa possessed simultaneously resistant to all antibiotics. Decesan and Miramistin had the same sensitivity P. aeruginosa (62.5± 8.94 μg∕ ml and 62.5±16,04 �

Derivation of guidelines for uranium residual radioactive material in soil at the Colonie Site, Colonie, New York

International Nuclear Information System (INIS)

Dunning, D.

1996-05-01

Residual radioactive material guidelines for uranium in soil were derived for the Colonie site located in Colonie, New York. This site has been designated for remedial action under the Formerly Utilized Sites Remedial Action Program (FUSRAP) of the U.S. Department of Energy (DOE). The site became contaminated with radioactive material as a result of operations conducted by National Lead (NL) Industries from 1958 to 1984; these activities included brass foundry operations, electroplating of metal products, machining of various components using depleted uranium, and limited work with small amounts of enriched uranium and thorium. The Colonie site comprises the former NL Industries property, now designated the Colonie Interim Storage Site (CISS), and 56 vicinity properties contaminated by fallout from airborne emissions; 53 of the vicinity properties were previously remediated between 1984 and 1988. In 1984, DOE accepted ownership of the CISS property from NL Industries. Residual radioactive material guidelines for individual radionuclides and total uranium were derived on the basis of the requirement that the 50-year committed effective dose equivalent to a hypothetical individual who lives or works in the immediate vicinity of the site should not exceed a dose of 30 mrem/yr following remedial action for the current use and likely future use scenarios or a dose of 100 mrem/yr for less likely future use scenarios. The DOE residual radioactive material guideline computer code, RESRAD, was used in this evaluation; RESRAD implements the methodology described in the DOE manual for establishing residual radioactive material guidelines

The cell wall and cell division gene cluster in the Mra operon of Pseudomonas aeruginosa: cloning, production, and purification of active enzymes.

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Azzolina, B A; Yuan, X; Anderson, M S; El-Sherbeini, M

2001-04-01

We have cloned the Pseudomonas aeruginosa cell wall biosynthesis and cell division gene cluster that corresponds to the mra operon in the 2-min region of the Escherichia coli chromosome. The organization of the two chromosomal regions in P. aeruginosa and E. coli is remarkably similar with the following gene order: pbp3/pbpB, murE, murF, mraY, murD, ftsW, murG, murC, ddlB, ftsQ, ftsA, ftsZ, and envA/LpxC. All of the above P. aeruginosa genes are transcribed from the same strand of DNA with very small, if any, intragenic regions, indicating that these genes may constitute a single operon. All five amino acid ligases, MurC, MurD, MurE, MurF, and DdlB, in addition to MurG and MraY were cloned in expression vectors. The four recombinant P. aeruginosa Mur ligases, MurC, MurD, MurE, and MurF were overproduced in E. coli and purified as active enzymes. Copyright 2001 Academic Press.

PAMDB: a comprehensive Pseudomonas aeruginosa metabolome database.

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Huang, Weiliang; Brewer, Luke K; Jones, Jace W; Nguyen, Angela T; Marcu, Ana; Wishart, David S; Oglesby-Sherrouse, Amanda G; Kane, Maureen A; Wilks, Angela

2018-01-04

The Pseudomonas aeruginosaMetabolome Database (PAMDB, http://pseudomonas.umaryland.edu) is a searchable, richly annotated metabolite database specific to P. aeruginosa. P. aeruginosa is a soil organism and significant opportunistic pathogen that adapts to its environment through a versatile energy metabolism network. Furthermore, P. aeruginosa is a model organism for the study of biofilm formation, quorum sensing, and bioremediation processes, each of which are dependent on unique pathways and metabolites. The PAMDB is modelled on the Escherichia coli (ECMDB), yeast (YMDB) and human (HMDB) metabolome databases and contains >4370 metabolites and 938 pathways with links to over 1260 genes and proteins. The database information was compiled from electronic databases, journal articles and mass spectrometry (MS) metabolomic data obtained in our laboratories. For each metabolite entered, we provide detailed compound descriptions, names and synonyms, structural and physiochemical information, nuclear magnetic resonance (NMR) and MS spectra, enzymes and pathway information, as well as gene and protein sequences. The database allows extensive searching via chemical names, structure and molecular weight, together with gene, protein and pathway relationships. The PAMBD and its future iterations will provide a valuable resource to biologists, natural product chemists and clinicians in identifying active compounds, potential biomarkers and clinical diagnostics. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

In situ growth rates and biofilm development of Pseudomonas aeruginosa populations in chronic lung infections

DEFF Research Database (Denmark)

Yang, L.; Haagensen, J.A.; Jelsbak, L.

2008-01-01

matrix, whereas nonmucoid variants were present mainly as dispersed cells. To obtain estimates of the growth rates of P. aeruginosa in CF lungs, we used quantitative FISH to indirectly measure growth rates of bacteria in sputum samples (reflecting the in vivo lung conditions). The concentration of r......The growth dynamics of bacterial pathogens within infected hosts are a fundamental but poorly understood feature of most infections. We have focused on the in situ distribution and growth characteristics of two prevailing and transmissible Pseudomonas aeruginosa clones that have caused chronic lung......RNA in bacteria isolated from sputa was measured and correlated with the rRNA contents of the same bacteria growing in vitro at defined rates. The results showed that most cells were actively growing with doubling times of between 100 and 200 min, with some growing even faster. Only a small stationary...

Clinical and Morphological Studies on Spontaneous Cases of Pseudomonas aeruginosa Infections in Birds

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I Dinev1, S Denev2* and G Beev2

2013-07-01

Full Text Available Clinical, pathoanatomical, histological, and bacteriological studies were performed on broiler chickens, growing broiler parents, and growing egg layers, in three different poultry farms, after an outbreak of Pseudomonas aeruginosa infections. The method of contamination of the birds was established. Several local and systemic clinico-morphological forms of spontaneous P. aeruginosa infections in various categories of stock birds were described: cases of P. aeruginosa infection resulting from injection of contaminated vaccines; case of P. aeruginosa infections through contaminated aerosol vaccine and cases of pododermatitis, periarthritis and arthritis in broiler chickens associated with P. aeruginosa infection. In different cases mortality range between 0.5 and 50%. The results showed that apart from embryonic mortality in hatcheries, and septicemic infections in newly hatched chickens, the pathogenicity of P. aeruginosa was associated with localized and systemic lesions in this category, as well as in young and growing birds. On one hand, these results have a theoretical significance, contributing for the confirmation and expansion of the wide array of clinico-morphological forms of P. aeruginosa infections in birds. On the other hand, the knowledge on these forms has a purely practical significance in the diagnostics of P. aeruginosa infections by poultry pathologists and veterinary practitioners.

A comparative study of coastal and clinical isolates of Pseudomonas aeruginosa

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Anusree V. Nair

2015-09-01

Full Text Available Pseudomonas aeruginosa is a ubiquitous Gram-negative bacterium having a versatile metabolic potential and great ecological and clinical significance. The geographical distribution of P. aeruginosahas revealed the existence of an unbiased genetic arrangement in terrestrial isolates. In contrast, there are very few reports about P. aeruginosa strains from marine environments. The present work was aimed at studying the distribution of P. aeruginosa in coastal waters along the Indian Peninsula and understanding the environmental influence on genotypic, metabolic and phenotypic characteristics by comparing marine and clinical isolates. Of the 785 marine isolates obtained on selective media, only 32 (~4.1% were identified as P. aeruginosa, based on their fatty acid methyl ester profiles. A low Euclidian distance value (P. aeruginosa. While biogeographical separation was not evident based solely on phenotypic and metabolic typing, genomic and metatranscriptomic studies are more likely to show differences between these isolates. Thus, newer and more insightful methods are required to understand the ecological distribution of this complex group of bacteria.

Influence of Pseudomonas aeruginosa on exacerbation in patients with bronchiectasis

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Kiran Chawla

2015-01-01

Full Text Available Background: A majority of the studies done on the western population have shown that Pseudomonas aeruginosa causes many severe infections in patients with bronchiectasis as compared to other pathogens. There is scarcity of similar data from the Asian population. Materials and Methods: A prospective study was undertaken to identify the various pathogens isolated from the respiratory samples of 117 patients with bronchiectasis from south India and to compare the clinicomicrobiological profile of infections caused by P. aeruginosa and other respiratory pathogens. Results: The respiratory pathogens were isolated from 63 (53.8% patients. P. aeruginosa was the most common isolate (46.0% followed by Klebsiella pneumoniae (14.3% and other pathogenic bacteria. Patients included in the P. aeruginosa group had a higher number of exacerbations (p: 0.008, greater number of hospital admissions (p: 0.007, a prolonged hospital stay (p: 0.03, and poor lung function, compared to the patients infected with the non-Pseudomonas group. Conclusion: It is necessary to investigate the etiology of respiratory tract infections among bronchiectasis patients followed by the prompt management of cases diagnosed with P. aeruginosa infections, so as to lower the morbidity and have a better prognosis.

Influence of feeding bee colonies on colony strenght and honey authenticity

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Andreja KANDOLF BOROVŠAK

2015-12-01

Full Text Available For the natural development of bee colonies, there is the need for appropriate nutrition. Lack of natural honey flow must be supplemented by feeding bee colonies with sugar syrups or candy paste. This supplementary feeding encourages brood breeding and forage activity, whereby stronger colonies collect more honey. Sugar syrups can cause honey adulteration, which is more frequent with the reversing of the brood combs with the bee food, with the combs moved from the brood chamber to the upper chamber. Authentication of honey from the standpoint of the presence of sugar syrup is very complex, because there is no single method by which honey adulteration can be reliably confirmed. Feeding the colonies in spring should result in stronger colonies and hence the collection of more honey in the brood chambers. The objective of the present study was to determine whether this has effects also on honey authenticity, and to discover a simple method for detection of honey adulteration. The colonies were fed with candy paste that had added yeast and blue dye, to provide markers for detection of honey adulteration. The strength of the colonies and quantity of honey in the brood chambers were monitored. The results of the analysis of stable isotope and activity of foreign enzymes were compared with the results of yeast quantity and colour of the honey (absorbance, L*, a*, b* parameters. Detection of yeast in the honey samples and presence of colour as a consequence of added dye appear to be appropriate methods to follow honey adulteration, and further studies are ongoing.

The resistome of Pseudomonas aeruginosa in relationship to phenotypic susceptibility.

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Kos, Veronica N; Déraspe, Maxime; McLaughlin, Robert E; Whiteaker, James D; Roy, Paul H; Alm, Richard A; Corbeil, Jacques; Gardner, Humphrey

2015-01-01

Many clinical isolates of Pseudomonas aeruginosa cause infections that are difficult to eradicate due to their resistance to a wide variety of antibiotics. Key genetic determinants of resistance were identified through genome sequences of 390 clinical isolates of P. aeruginosa, obtained from diverse geographic locations collected between 2003 and 2012 and were related to microbiological susceptibility data for meropenem, levofloxacin, and amikacin. β-Lactamases and integron cassette arrangements were enriched in the established multidrug-resistant lineages of sequence types ST111 (predominantly O12) and ST235 (O11). This study demonstrates the utility of next-generation sequencing (NGS) in defining relevant resistance elements and highlights the diversity of resistance determinants within P. aeruginosa. This information is valuable in furthering the design of diagnostics and therapeutics for the treatment of P. aeruginosa infections. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Redox-active antibiotics control gene expression and community behavior in divergent bacteria.

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Dietrich, Lars E P; Teal, Tracy K; Price-Whelan, Alexa; Newman, Dianne K

2008-08-29

It is thought that bacteria excrete redox-active pigments as antibiotics to inhibit competitors. In Pseudomonas aeruginosa, the endogenous antibiotic pyocyanin activates SoxR, a transcription factor conserved in Proteo- and Actinobacteria. In Escherichia coli, SoxR regulates the superoxide stress response. Bioinformatic analysis coupled with gene expression studies in P. aeruginosa and Streptomyces coelicolor revealed that the majority of SoxR regulons in bacteria lack the genes required for stress responses, despite the fact that many of these organisms still produce redox-active small molecules, which indicates that redox-active pigments play a role independent of oxidative stress. These compounds had profound effects on the structural organization of colony biofilms in both P. aeruginosa and S. coelicolor, which shows that "secondary metabolites" play important conserved roles in gene expression and development.

Cystic fibrosis-niche adaptation of Pseudomonas aeruginosa reduces virulence in multiple infection hosts.

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Nicola Ivan Lorè

Full Text Available The opportunistic pathogen Pseudomonas aeruginosa is able to thrive in diverse ecological niches and to cause serious human infection. P. aeruginosa environmental strains are producing various virulence factors that are required for establishing acute infections in several host organisms; however, the P. aeruginosa phenotypic variants favour long-term persistence in the cystic fibrosis (CF airways. Whether P. aeruginosa strains, which have adapted to the CF-niche, have lost their competitive fitness in the other environment remains to be investigated. In this paper, three P. aeruginosa clonal lineages, including early strains isolated at the onset of infection, and late strains, isolated after several years of chronic lung infection from patients with CF, were analysed in multi-host model systems of acute infection. P. aeruginosa early isolates caused lethality in the three non-mammalian hosts, namely Caenorhabditis elegans, Galleria mellonella, and Drosophila melanogaster, while late adapted clonal isolates were attenuated in acute virulence. When two different mouse genetic background strains, namely C57Bl/6NCrl and Balb/cAnNCrl, were used as acute infection models, early P. aeruginosa CF isolates were lethal, while late isolates exhibited reduced or abolished acute virulence. Severe histopathological lesions, including high leukocytes recruitment and bacterial load, were detected in the lungs of mice infected with P. aeruginosa CF early isolates, while late isolates were progressively cleared. In addition, systemic bacterial spread and invasion of epithelial cells, which were detected for P. aeruginosa CF early strains, were not observed with late strains. Our findings indicate that niche-specific selection in P. aeruginosa reduced its ability to cause acute infections across a broad range of hosts while maintaining the capacity for chronic infection in the CF host.

Intraclonal genome diversity of Pseudomonas aeruginosa clones CHA and TB

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2013-01-01

Background Adaptation of Pseudomonas aeruginosa to different living conditions is accompanied by microevolution resulting in genomic diversity between strains of the same clonal lineage. In order to detect the impact of colonized habitats on P. aeruginosa microevolution we determined the genomic diversity between the highly virulent cystic fibrosis (CF) isolate CHA and two temporally and geographically unrelated clonal variants. The outcome was compared with the intraclonal genome diversity between three more closely related isolates of another clonal complex. Results The three clone CHA isolates differed in their core genome in several dozen strain specific nucleotide exchanges and small deletions from each other. Loss of function mutations and non-conservative amino acid replacements affected several habitat- and lifestyle-associated traits, for example, the key regulator GacS of the switch between acute and chronic disease phenotypes was disrupted in strain CHA. Intraclonal genome diversity manifested in an individual composition of the respective accessory genome whereby the highest number of accessory DNA elements was observed for isolate PT22 from a polluted aquatic habitat. Little intraclonal diversity was observed between three spatiotemporally related outbreak isolates of clone TB. Although phenotypically different, only a few individual SNPs and deletions were detected in the clone TB isolates. Their accessory genome mainly differed in prophage-like DNA elements taken up by one of the strains. Conclusions The higher geographical and temporal distance of the clone CHA isolates was associated with an increased intraclonal genome diversity compared to the more closely related clone TB isolates derived from a common source demonstrating the impact of habitat adaptation on the microevolution of P. aeruginosa. However, even short-term habitat differentiation can cause major phenotypic diversification driven by single genomic variation events and uptake of phage

Pseudomonas aeruginosa keratitis: outcomes and response to corticosteroid treatment.

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Sy, Aileen; Srinivasan, Muthiah; Mascarenhas, Jeena; Lalitha, Prajna; Rajaraman, Revathi; Ravindran, Meenakshi; Oldenburg, Catherine E; Ray, Kathryn J; Glidden, David; Zegans, Michael E; McLeod, Stephen D; Lietman, Thomas M; Acharya, Nisha R

2012-01-25

To compare the clinical course and effect of adjunctive corticosteroid therapy in Pseudomonas aeruginosa with those of all other strains of bacterial keratitis. Subanalyses were performed on data collected in the Steroids for Corneal Ulcers Trial (SCUT), a large randomized controlled trial in which patients were treated with moxifloxacin and were randomly assigned to 1 of 2 adjunctive treatment arms: corticosteroid or placebo (4 times a day with subsequent reduction). Multivariate analysis was used to determine the effect of predictors, organism, and treatment on outcomes, 3-month best-spectacle-corrected visual acuity (BSCVA), and infiltrate/scar size. The incidence of adverse events over a 3-month follow-up period was compared using Fisher's exact test. SCUT enrolled 500 patients. One hundred ten patients had P. aeruginosa ulcers; 99 of 110 (90%) enrolled patients returned for follow-up at 3 months. Patients with P. aeruginosa ulcers had significantly worse visual acuities than patients with other bacterial ulcers (P = 0.001) but showed significantly more improvement in 3-month BSCVA than those with other bacterial ulcers, adjusting for baseline characteristics (-0.14 logMAR; 95% confidence interval, -0.23 to -0.04; P = 0.004). There was no significant difference in adverse events between P. aeruginosa and other bacterial ulcers. There were no significant differences in BSCVA (P = 0.69), infiltrate/scar size (P = 0.17), and incidence of adverse events between patients with P. aeruginosa ulcers treated with adjunctive corticosteroids and patients given placebo. Although P. aeruginosa corneal ulcers have a more severe presentation, they appear to respond better to treatment than other bacterial ulcers. The authors did not find a significant benefit with corticosteroid treatment, but they also did not find any increase in adverse events. (ClinicalTrials.gov number, NCT00324168.).

Family strategies against the jesuits in colonial Argentina: Catamarca, 1683-1767

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Jorge Troisi Melean

2012-11-01

Full Text Available Based on a lawsuit, I will conduct a detailed study of the strategies of Catamarca´s colonial settlers to deal with Society of Jesus, the most powerful institution of the time.Three families were fighting for survival in a small colonial town in a middle of intercontinental fight between a forceful Spanish Crown and a hesitant Catholic Church. In the gaps of that struggle, each family negotiated their identity against a multiplicity of interests in play, seeking the best of possibilities in a world that was rapidly changing.

Obesity emergence in the Pacific islands: why understanding colonial history and social change is important.

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McLennan, Amy K; Ulijaszek, Stanley J

2015-06-01

Between 1980 and 2008, two Pacific island nations - Nauru and the Cook Islands - experienced the fastest rates of increasing BMI in the world. Rates were over four times higher than the mean global BMI increase. The aim of the present paper is to examine why these populations have been so prone to obesity increases in recent times. Three explanatory frames that apply to both countries are presented: (i) geographic isolation and genetic predisposition; (ii) small population and low food production capacity; and (iii) social change under colonial influence. These are compared with social changes documented by anthropologists during the colonial and post-colonial periods. Nauru and the Cook Islands. While islands are isolated, islanders are interconnected. Similarly, islands are small, but land use is socially determined. While obesity affects individuals, islanders are interdependent. New social values, which were rapidly propagated through institutions such as the colonial system of education and the cash economy, are today reflected in all aspects of islander life, including diet. Such historical social changes may predispose societies to obesity. Colonial processes may have put in place the conditions for subsequent rapidly escalating obesity. Of the three frameworks discussed, social change under colonial influence is not immutable to further change in the future and could take place rapidly. In theorising obesity emergence in the Pacific islands, there is a need to incorporate the idea of obesity being a product of interdependence and interconnectedness, rather than independence and individual choice.

The genetics of colony form and function in Caribbean Acropora corals.

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Hemond, Elizabeth M; Kaluziak, Stefan T; Vollmer, Steven V

2014-12-17

Colonial reef-building corals have evolved a broad spectrum of colony morphologies based on coordinated asexual reproduction of polyps on a secreted calcium carbonate skeleton. Though cnidarians have been shown to possess and use similar developmental genes to bilaterians during larval development and polyp formation, little is known about genetic regulation of colony morphology in hard corals. We used RNA-seq to evaluate transcriptomic differences between functionally distinct regions of the coral (apical branch tips and branch bases) in two species of Caribbean Acropora, the staghorn coral, A. cervicornis, and the elkhorn coral, A. palmata. Transcriptome-wide gene profiles differed significantly between different parts of the coral colony as well as between species. Genes showing differential expression between branch tips and bases were involved in developmental signaling pathways, such as Wnt, Notch, and BMP, as well as pH regulation, ion transport, extracellular matrix production and other processes. Differences both within colonies and between species identify a relatively small number of genes that may contribute to the distinct "staghorn" versus "elkhorn" morphologies of these two sister species. The large number of differentially expressed genes supports a strong division of labor between coral branch tips and branch bases. Genes involved in growth of mature Acropora colonies include the classical signaling pathways associated with development of cnidarian larvae and polyps as well as morphological determination in higher metazoans.

Chronic Pseudomonas aeruginosa lung infection in normal and athymic rats

DEFF Research Database (Denmark)

Johansen, H K; Espersen, F; Pedersen, S S

1993-01-01

We have compared a chronic lung infection with Pseudomonas aeruginosa embedded in alginate beads in normal and athymic rats with an acute infection with free live P. aeruginosa bacteria. The following parameters were observed and described: mortality, macroscopic and microscopic pathologic changes...

Multiple roles of biosurfactants in structural biofilm development by Pseudomonas aeruginosa

DEFF Research Database (Denmark)

Pamp, Sünje Johanna; Tolker-Nielsen, Tim

2007-01-01

Recent studies have indicated that biosurfactants produced by Pseudomonas aeruginosa play a role both in maintaining channels between multicellular structures in biofilms and in dispersal of cells from biofilms. Through the use of flow cell technology and enhanced confocal laser scanning microscopy......, we have obtained results which suggest that the biosurfactants produced by P. aeruginosa play additional roles in structural biofilm development. We present genetic evidence that during biofilm development by P. aeruginosa, biosurfactants promote microcolony formation in the initial phase...... and facilitate migration-dependent structural development in the later phase. P. aeruginosa rhl4 mutants, deficient in synthesis of biosurfactants, were not capable of forming microcolonies in the initial phase of biofilm formation. Experiments involving two-color-coded mixed-strain biofilms showed that P...

Electrochemical reduction of oxygen catalyzed by Pseudomonas aeruginosa

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Cournet, Amandine [Universite de Toulouse, UPS, LU49, Adhesion bacterienne et formation de biofilms, 35 chemin des Maraichers, 31062 Toulouse Cedex 09 (France)] [Laboratoire de Genie Chimique CNRS UMR5503, 4 allee Emile Monso, BP 84234, 31432 Toulouse Cedex 04 (France); Berge, Mathieu; Roques, Christine [Universite de Toulouse, UPS, LU49, Adhesion bacterienne et formation de biofilms, 35 chemin des Maraichers, 31062 Toulouse Cedex 09 (France); Bergel, Alain [Laboratoire de Genie Chimique CNRS UMR5503, 4 allee Emile Monso, BP 84234, 31432 Toulouse Cedex 04 (France); Delia, Marie-Line, E-mail: marieline.delia@ensiacet.f [Laboratoire de Genie Chimique CNRS UMR5503, 4 allee Emile Monso, BP 84234, 31432 Toulouse Cedex 04 (France)

2010-07-01

Pseudomonas aeruginosa has already been shown to catalyze oxidation processes in the anode compartment of a microbial fuel cell. The present study focuses on the reverse capacity of the bacterium, i.e. reduction catalysis. Here we show that P. aeruginosa is able to catalyze the electrochemical reduction of oxygen. The use of cyclic voltammetry showed that, for a given range of potential values, the current generated in the presence of bacteria could reach up to four times the current obtained without bacteria. The adhesion of bacteria to the working electrode was necessary for the catalysis to be observed but was not sufficient. The electron transfer between the working electrode and the bacteria did not involve mediator metabolites like phenazines. The transfer was by direct contact. The catalysis required a certain contact duration between electrodes and live bacteria but after this delay, the metabolic activity of cells was no longer necessary. Membrane-bound proteins, like catalase, may be involved. Various strains of P. aeruginosa, including clinical isolates, were tested and all of them, even catalase-defective mutants, presented the same catalytic property. P. aeruginosa offers a new model for the analysis of reduction catalysis and the protocol designed here may provide a basis for developing an interesting tool in the field of bacterial adhesion.

Activation of the lectin pathway of complement in experimental human keratitis with Pseudomonas aeruginosa.

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Osthoff, Michael; Brown, Karl D; Kong, David C M; Daniell, Mark; Eisen, Damon P

2014-01-01

Pseudomonas aeruginosa (P. aeruginosa) microbial keratitis (MK) is a sight-threatening disease. Previous animal studies have identified an important contribution of the complement system to the clearance of P. aeruginosa infection of the cornea. Mannose-binding lectin (MBL), a pattern recognition receptor of the lectin pathway of complement, has been implicated in the host defense against P. aeruginosa. However, studies addressing the role of the lectin pathway in P. aeruginosa MK are lacking. Hence, we sought to determine the activity of the lectin pathway in human MK caused by P. aeruginosa. Primary human corneal epithelial cells (HCECs) from cadaveric donors were exposed to two different P. aeruginosa strains. Gene expression of interleukin (IL)-6, IL-8, MBL, and other complement proteins was determined by reverse transcription-polymerase chain reaction (RT-PCR) and MBL synthesis by enzyme-linked immunosorbent assay and intracellular flow cytometry. MBL gene expression was not detected in unchallenged HCECs. Exposure of HCECs to P. aeruginosa resulted in rapid induction of the transcriptional expression of MBL, IL-6, and IL-8. In addition, expression of several complement proteins of the classical and lectin pathways, but not the alternative pathway, were upregulated after 5 h of challenge, including MBL-associated serine protease 1. However, MBL protein secretion was not detectable 18 h after challenge with P. aeruginosa. MK due to P. aeruginosa triggers activation of MBL and the lectin pathway of complement. However, the physiologic relevance of this finding is unclear, as corresponding MBL oligomer production was not observed.

Cooperative pathogenicity in cystic fibrosis: Stenotrophomonas maltophilia modulates Pseudomonas aeruginosa virulence in mixed biofilm

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Arianna ePompilio

2015-09-01

Full Text Available The present study was undertaken in order to understand more about the interaction occurring between S. maltophilia and P. aeruginosa, which are frequently co-isolated from CF airways. For this purpose, S. maltophilia RR7 and P. aeruginosa RR8 strains, co-isolated from the lung of a chronically infected CF patient during a pulmonary exacerbation episode, were evaluated for reciprocal effect during planktonic growth, adhesion and biofilm formation onto both polystyrene and CF bronchial cell monolayer, motility, as well as for gene expression in mixed biofilms. P. aeruginosa significantly affected S. maltophilia growth in both planktonic and biofilm cultures, due to an inhibitory activity probably requiring direct contact. Conversely, no effect was observed on P. aeruginosa by S. maltophilia. Compared with monocultures, the adhesiveness of P. aeruginosa on CFBE41o- cells was significantly reduced by S. maltophilia, which probably acts by reducing P. aeruginosa's swimming motility. An opposite trend was observed for biofilm formation, confirming the findings obtained using polystyrene. When grown in mixed biofilm with S. maltophilia, P. aeruginosa significantly over-expressed aprA, and algD - codifying for protease and alginate, respectively - while the quorum sensing related rhlR and lasI genes were down-regulated. The induced alginate expression by P. aeruginosa might be responsible for the protection of S. maltophilia against tobramycin activity we observed in mixed biofilms. Taken together, our results suggest that the existence of reciprocal interference of S. maltophilia and P. aeruginosa in CF lung is plausible. In particular, S. maltophilia might confer some selective fitness advantage to P. aeruginosa under the specific conditions of chronic infection or, alternatively, increase the virulence of P. aeruginosa thus leading to pulmonary exacerbation.

Hemorrhagic pneumonia in mink caused by Pseudomonas aeruginosa

DEFF Research Database (Denmark)

Salomonsen, Charlotte Mark

research has been performed in this field and most published work is more than 25 years old. The studies presented in this thesis aim at elucidating varying aspects of the disease: Article I investigates the relationships of P. aeruginosa isolated from mink hemorrhagic pneumonia using pulsed field gel...... electrophoresis (PFGE) and a commercial typing system based on single nucleotide polymorphisms (SNP) on chosen strains. The results presented in this article show that 70% of P. aeruginosa isolated from outbreaks of hemorrhagic pneumonia in mink consist of unique strains, while the remaining 30% belongs to either...... in hemorrhagic pneumonia caused by P. aeruginosa and E. coli in diagnostic material. The distribution of the two pathogens is visualized using fluorescence in situ hybridization (FISH). Two histological patterns were observed in the work presented in Article II; one was very hemorrhagic with few bacteria while...

Review Essay A history of colonialism through post-colonial lenses ...

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Review Essay A history of colonialism through post-colonial lenses: reading Mahmood Mamdani's citizen and subject. Sanya Osha. Abstract. No Abstract. The Nigerian Journal of Economic History Vol. 2, 1999: 155-161. Full Text: EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT.

Identification of Pseudomonas aeruginosa phenazines that kill Caenorhabditis elegans.

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Cezairliyan, Brent; Vinayavekhin, Nawaporn; Grenfell-Lee, Daniel; Yuen, Grace J; Saghatelian, Alan; Ausubel, Frederick M

2013-01-01

Pathogenic microbes employ a variety of methods to overcome host defenses, including the production and dispersal of molecules that are toxic to their hosts. Pseudomonas aeruginosa, a Gram-negative bacterium, is a pathogen of a diverse variety of hosts including mammals and the nematode Caenorhabditis elegans. In this study, we identify three small molecules in the phenazine class that are produced by P. aeruginosa strain PA14 that are toxic to C. elegans. We demonstrate that 1-hydroxyphenazine, phenazine-1-carboxylic acid, and pyocyanin are capable of killing nematodes in a matter of hours. 1-hydroxyphenazine is toxic over a wide pH range, whereas the toxicities of phenazine-1-carboxylic acid and pyocyanin are pH-dependent at non-overlapping pH ranges. We found that acidification of the growth medium by PA14 activates the toxicity of phenazine-1-carboxylic acid, which is the primary toxic agent towards C. elegans in our assay. Pyocyanin is not toxic under acidic conditions and 1-hydroxyphenazine is produced at concentrations too low to kill C. elegans. These results suggest a role for phenazine-1-carboxylic acid in mammalian pathogenesis because PA14 mutants deficient in phenazine production have been shown to be defective in pathogenesis in mice. More generally, these data demonstrate how diversity within a class of metabolites could affect bacterial toxicity in different environmental niches.

Identification of Pseudomonas aeruginosa phenazines that kill Caenorhabditis elegans.

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Brent Cezairliyan

2013-01-01

Full Text Available Pathogenic microbes employ a variety of methods to overcome host defenses, including the production and dispersal of molecules that are toxic to their hosts. Pseudomonas aeruginosa, a Gram-negative bacterium, is a pathogen of a diverse variety of hosts including mammals and the nematode Caenorhabditis elegans. In this study, we identify three small molecules in the phenazine class that are produced by P. aeruginosa strain PA14 that are toxic to C. elegans. We demonstrate that 1-hydroxyphenazine, phenazine-1-carboxylic acid, and pyocyanin are capable of killing nematodes in a matter of hours. 1-hydroxyphenazine is toxic over a wide pH range, whereas the toxicities of phenazine-1-carboxylic acid and pyocyanin are pH-dependent at non-overlapping pH ranges. We found that acidification of the growth medium by PA14 activates the toxicity of phenazine-1-carboxylic acid, which is the primary toxic agent towards C. elegans in our assay. Pyocyanin is not toxic under acidic conditions and 1-hydroxyphenazine is produced at concentrations too low to kill C. elegans. These results suggest a role for phenazine-1-carboxylic acid in mammalian pathogenesis because PA14 mutants deficient in phenazine production have been shown to be defective in pathogenesis in mice. More generally, these data demonstrate how diversity within a class of metabolites could affect bacterial toxicity in different environmental niches.

Effects of ambroxol on biofilm adhesion and viability of Pseudomonas aeruginosa quorum sensing defective strain

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Qi LU

2013-07-01

Full Text Available Objective　To investigate the effects of ambroxol on the biofilm viability and pristine adhesion of Pseudomonas aeruginosa wild (PAO1 and quorum sensing defective strain (QS, gene deletion of ∆lasI and ∆rhlI. Methods　The biofilm was treated by different concentrations (0, 1.875, 3.75mg/ml of ambroxol. The number of colony was measured with agar plate, multifunction fluorometer was used to measure the fluorescence intensity of PAO1 and QS strains at the bottom of 96-well plate. The adhesion ratio (% was calculated to determine the effects of ambroxol on bacterial biofilm adhesion. Results　Ambroxol treatment reduced the survival rate of the mutant strains compared to that of wild strain, even though the QS strain had increased the adhesion in the presence of ambroxol compared to that of wild strain (P<0.05. Conclusion　Ambroxol has a property of significantly antagonizing quorum-sensing system, suggesting that it might be of importance in treatment against chronic Pseudomonasaeruginosainfections.

Spatial Distribution of Lactococcus lactis Colonies Modulates the Production of Major Metabolites during the Ripening of a Model Cheese.

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Le Boucher, Clémentine; Gagnaire, Valérie; Briard-Bion, Valérie; Jardin, Julien; Maillard, Marie-Bernadette; Dervilly-Pinel, Gaud; Le Bizec, Bruno; Lortal, Sylvie; Jeanson, Sophie; Thierry, Anne

2016-01-01

In cheese, lactic acid bacteria are immobilized at the coagulation step and grow as colonies. The spatial distribution of bacterial colonies is characterized by the size and number of colonies for a given bacterial population within cheese. Our objective was to demonstrate that different spatial distributions, which lead to differences in the exchange surface between the colonies and the cheese matrix, can influence the ripening process. The strategy was to generate cheeses with the same growth and acidification of a Lactococcus lactis strain with two different spatial distributions, big and small colonies, to monitor the production of the major ripening metabolites, including sugars, organic acids, peptides, free amino acids, and volatile metabolites, over 1 month of ripening. The monitored metabolites were qualitatively the same for both cheeses, but many of them were more abundant in the small-colony cheeses than in the big-colony cheeses over 1 month of ripening. Therefore, the results obtained showed that two different spatial distributions of L. lactis modulated the ripening time course by generating moderate but significant differences in the rates of production or consumption for many of the metabolites commonly monitored throughout ripening. The present work further explores the immobilization of bacteria as colonies within cheese and highlights the consequences of this immobilization on cheese ripening. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Arsenate biotransformation by Microcystis aeruginosa under different nitrogen and phosphorus levels.

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Che, Feifei; Du, Miaomiao; Yan, Changzhou

2018-04-01

The arsenate (As(V)) biotransformation by Microcystis aeruginosa in a medium with different concentrations of nitrogen (N) and phosphorus (P) has been studied under laboratory conditions. When 15μg/L As(V) was added, N and P in the medium showed effective regulation on arsenic (As) metabolism in M. aeruginosa, resulting in significant differences in the algal growth among different N and P treatments. Under 0.2mg/L P treatment, increases in N concentration (4-20mg/L) significantly stimulated the cell growth and therefore indirectly enhanced the production of dimethylarsinic acid (DMA), the main As metabolite, accounting for 71%-79% of the total As in the medium. Meanwhile, 10-20mg/L N treatments accelerated the ability of As metabolization by M. aeruginosa, leading to higher contents of DMA per cell. However, As(V) uptake by M. aeruginosa was significantly impeded by 0.5-1.0mg/L P treatment, resulting in smaller rates of As transformation in M. aeruginosa as well as lower contents of As metabolites in the medium. Our data demonstrated that As(V) transformation by M. aeruginosa was significantly accelerated by increasing N levels, while it was inhibited by increasing P levels. Overall, both P and N play key roles in As(V) biotransformation processes. Copyright © 2017. Published by Elsevier B.V.

Balneotherapy is a potential risk factor for Pseudomonas aeruginosa colonization

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Gabriela Deutsch

Full Text Available ABSTRACT The practice of immersion in burn patient has been abandoned in many parts of the world but in Brazil it is still common. The aim of this study was to ascertain if balneotherapy is a risk factor for Pseudomonas aeruginosa colonization in thermally injured patients. Eighteen patients from a Burn Center were studied for 14 weeks for Pseudomonas aeruginosa. Samples were collected by swabbing the exudate of wounds, before and after giving bath to the patients and from balneotherapy table. Pulsed-field gel electrophoresis was used to determine bacterial genetic relatedness. Thirty-seven P. aeruginosa isolates were detected from 292 swabs collected from patients' burn surface area and from the balneotherapy table. Profile analysis of P. aeruginosa DNA fragmentation showed 10 clones among the 37 strains analyzed. Type A is the most prevalent clone, with 23 strains distributed into eight subtypes. These were present in the swabs collected, before and after the patients' bath, from the surface of the bath table, suggesting that there was cross-contamination between the patients in different ways. This work demonstrates that balneotherapy is a risk factor in the Burn Center studied, because the same clone was found among P. aeruginosa isolates collected at various points and times.

Selective binding and oligomerization of the murine granulocyte colony-stimulating factor receptor by a low molecular weight, nonpeptidyl ligand.

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Doyle, Michael L; Tian, Shin-Shay; Miller, Stephen G; Kessler, Linda; Baker, Audrey E; Brigham-Burke, Michael R; Dillon, Susan B; Duffy, Kevin J; Keenan, Richard M; Lehr, Ruth; Rosen, Jon; Schneeweis, Lumelle A; Trill, John; Young, Peter R; Luengo, Juan I; Lamb, Peter

2003-03-14

Granulocyte colony-stimulating factor regulates neutrophil production by binding to a specific receptor, the granulocyte colony-stimulating factor receptor, expressed on cells of the granulocytic lineage. Recombinant forms of granulocyte colony-stimulating factor are used clinically to treat neutropenias. As part of an effort to develop granulocyte colony-stimulating factor mimics with the potential for oral bioavailability, we previously identified a nonpeptidyl small molecule (SB-247464) that selectively activates murine granulocyte colony-stimulating factor signal transduction pathways and promotes neutrophil formation in vivo. To elucidate the mechanism of action of SB-247464, a series of cell-based and biochemical assays were performed. The activity of SB-247464 is strictly dependent on the presence of zinc ions. Titration microcalorimetry experiments using a soluble murine granulocyte colony-stimulating factor receptor construct show that SB-247464 binds to the extracellular domain of the receptor in a zinc ion-dependent manner. Analytical ultracentrifugation studies demonstrate that SB-247464 induces self-association of the N-terminal three-domain fragment in a manner that is consistent with dimerization. SB-247464 induces internalization of granulocyte colony-stimulating factor receptor on intact cells, consistent with a mechanism involving receptor oligomerization. These data show that small nonpeptidyl compounds are capable of selectively binding and inducing productive oligomerization of cytokine receptors.

Microbiome of Trichodesmium Colonies from the North Pacific Subtropical Gyre

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Mary R. Gradoville

2017-07-01

Full Text Available Filamentous diazotrophic Cyanobacteria of the genus Trichodesmium, often found in colonial form, provide an important source of new nitrogen to tropical and subtropical marine ecosystems. Colonies are composed of several clades of Trichodesmium in association with a diverse community of bacterial and eukaryotic epibionts. We used high-throughput 16S rRNA and nifH gene sequencing, carbon (C and dinitrogen (N2 fixation assays, and metagenomics to describe the diversity and functional potential of the microbiome associated with Trichodesmium colonies collected from the North Pacific Subtropical Gyre (NPSG. The 16S rRNA and nifH gene sequences from hand-picked colonies were predominantly (>99% from Trichodesmium Clade I (i.e., T. thiebautii, which is phylogenetically and ecologically distinct from the Clade III IMS101 isolate used in most laboratory studies. The bacterial epibiont communities were dominated by Bacteroidetes, Alphaproteobacteria, and Gammaproteobacteria, including several taxa with a known preference for surface attachment, and were relatively depleted in the unicellular Cyanobacteria and small photoheterotrophic bacteria that dominate NPSG surface waters. Sequencing the nifH gene (encoding a subcomponent of the nitrogenase enzyme identified non-Trichodesmium diazotrophs that clustered predominantly among the Cluster III nifH sequence-types that includes putative anaerobic diazotrophs. Trichodesmium colonies may represent an important habitat for these Cluster III diazotrophs, which were relatively rare in the surrounding seawater. Sequence analyses of nifH gene transcripts revealed several cyanobacterial groups, including heterocystous Richelia, associated with the colonies. Both the 16S rRNA and nifH datasets indicated strong differences between Trichodesmium epibionts and picoplankton in the surrounding seawater, and also between the epibionts inhabiting Trichodesmium puff and tuft colony morphologies. Metagenomic and 16S r

Comparative activities of ciprofloxacin, ticarcillin, and tobramycin against experimental Pseudomonas aeruginosa pneumonia.

OpenAIRE

Schiff, J B; Small, G J; Pennington, J E

1984-01-01

The therapeutic efficacy of ciprofloxacin, an investigational quinoline derivative, was compared with those of ticarcillin and tobramycin in guinea pigs with experimental Pseudomonas aeruginosa pneumonia. Guinea pigs challenged with tracheal instillations of 10(8) CFU of P. aeruginosa developed acute pneumonia, for which survival rates were: controls, 0%; ticarcillin treatment, 37%; ciprofloxacin treatment, 57%; and tobramycin treatment, 69%. Intrapulmonary killing of P. aeruginosa was greate...

Intricate interactions between the bloom-forming cyanobacterium Microcystis aeruginosa and foreign genetic elements, revealed by diversified clustered regularly interspaced short palindromic repeat (CRISPR) signatures.

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Kuno, Sotaro; Yoshida, Takashi; Kaneko, Takakazu; Sako, Yoshihiko

2012-08-01

Clustered regularly interspaced short palindromic repeats (CRISPR) confer sequence-dependent, adaptive resistance in prokaryotes against viruses and plasmids via incorporation of short sequences, called spacers, derived from foreign genetic elements. CRISPR loci are thus considered to provide records of past infections. To describe the host-parasite (i.e., cyanophages and plasmids) interactions involving the bloom-forming freshwater cyanobacterium Microcystis aeruginosa, we investigated CRISPR in four M. aeruginosa strains and in two previously sequenced genomes. The number of spacers in each locus was larger than the average among prokaryotes. All spacers were strain specific, except for a string of 11 spacers shared in two closely related strains, suggesting diversification of the loci. Using CRISPR repeat-based PCR, 24 CRISPR genotypes were identified in a natural cyanobacterial community. Among 995 unique spacers obtained, only 10 sequences showed similarity to M. aeruginosa phage Ma-LMM01. Of these, six spacers showed only silent or conservative nucleotide mutations compared to Ma-LMM01 sequences, suggesting a strategy by the cyanophage to avert CRISPR immunity dependent on nucleotide identity. These results imply that host-phage interactions can be divided into M. aeruginosa-cyanophage combinations rather than pandemics of population-wide infectious cyanophages. Spacer similarity also showed frequent exposure of M. aeruginosa to small cryptic plasmids that were observed only in a few strains. Thus, the diversification of CRISPR implies that M. aeruginosa has been challenged by diverse communities (almost entirely uncharacterized) of cyanophages and plasmids.

Using interval maxima regression (IMR) to determine environmental optima controlling Microcystis spp. growth in Lake Taihu.

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Li, Ming; Peng, Qiang; Xiao, Man

2016-01-01

Fortnightly investigations at 12 sampling sites in Meiliang Bay and Gonghu Bay of Lake Taihu (China) were carried out from June to early November 2010. The relationship between abiotic factors and cell density of different Microcystis species was analyzed using the interval maxima regression (IMR) to determine the optimum temperature and nutrient concentrations for growth of different Microcystis species. Our results showed that cell density of all the Microcystis species increased along with the increase of water temperature, but Microcystis aeruginosa adapted to a wide range of temperatures. The optimum total dissolved nitrogen concentrations for M. aeruginosa, Microcystis wesenbergii, Microcystis ichthyoblabe, and unidentified Microcystis were 3.7, 2.0, 2.4, and 1.9 mg L(-1), respectively. The optimum total dissolved phosphorus concentrations for different species were M. wesenbergii (0.27 mg L(-1)) > M. aeruginosa (0.1 mg L(-1)) > M. ichthyoblabe (0.06 mg L(-1)) ≈ unidentified Microcystis, and the iron (Fe(3+)) concentrations were M. wesenbergii (0.73 mg L(-1)) > M. aeruginosa (0.42 mg L(-1)) > M. ichthyoblabe (0.35 mg L(-1)) > unidentified Microcystis (0.09 mg L(-1)). The above results suggest that if phosphorus concentration was reduced to 0.06 mg L(-1) or/and iron concentration was reduced to 0.35 mg L(-1) in Lake Taihu, the large colonial M. wesenbergii and M. aeruginosa would be replaced by small colonial M. ichthyoblabe and unidentified Microcystis. Thereafter, the intensity and frequency of the occurrence of Microcystis blooms would be reduced by changing Microcystis species composition.

Colonial Legal Reasoning in the Post-Colonial African State: A ...

African Journals Online (AJOL)

Colonial Legal Reasoning in the Post-Colonial African State: A Critique and a Defense of the Argument from African Metaphysical Epistemology. ... Africa, as it has the advantageous result of helping in the search for truth concerning such offences, thereby promoting the delivery of effective legal justice, and thus contributing ...

Life in the colonies: learning the alien ways of colonial organisms.

Science.gov (United States)

Winston, Judith E

2010-12-01

Who needs to go to outer space to study alien beings when the oceans of our own planet abound with bizarre and unknown creatures? Many of them belong to sessile clonal and colonial groups, including sponges, hydroids, corals, octocorals, ascidians, bryozoans, and some polychaetes. Their life histories, in many ways unlike our own, are a challenge for biologists. Studying their ecology, behavior, and taxonomy means trying to “think like a colony” to understand the factors important in their lives. Until the 1980s, most marine ecologists ignored these difficult modular organisms. Plant ecologists showed them ways to deal with the two levels of asexually produced modules and genetic individuals, leading to a surge in research on the ecology of clonal and colonial marine invertebrates. Bryozoans make excellent model colonial animals. Their life histories range from ephemeral to perennial. Aspects of their lives such as growth, reproduction, partial mortality due to predation or fouling, and the behavior of both autozooids and polymorphs can be studied at the level of the colony, as well as that of the individual module, in living colonies and over time.

Dealing with water deficit in Atta ant colonies: large ants scout for water while small ants transport it

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Antonio Carlos Da-Silva

2012-07-01

Leafcutter ants (Atta sexdens rubropilosa (Forel 1908 have an elaborate social organization, complete with caste divisions. Activities carried out by specialist groups contribute to the overall success and survival of the colony when it is confronted with environmental challenges such as dehydration. Ants detect variations in humidity inside the nest and react by activating several types of behavior that enhance water uptake and decrease water loss, but it is not clear whether or not a single caste collects water regardless of the cost of bringing this resource back to the colony. Accordingly, we investigated water collection activities in three colonies of Atta sexdens rubropilosa experimentally exposed to water stress. Specifically, we analyzed whether or not the same ant caste foraged for water, regardless of the absolute energetic cost (distance of transporting this resource back to the colony. Our experimental design offered water sources at 0 m, 1 m and 10 m from the nest. We studied the body size of ants near the water sources from the initial offer of water (time  =  0 to 120 min, and tested for specialization. We observed a reduction in the average size and variance of ants that corroborated the specialization hypothesis. Although the temporal course of specialization changed with distance, the final outcome was similar among distances. Thus, we conclude that, for this species, a specialist (our use of the word “specialist” does not mean exclusive task force is responsible for collecting water, regardless of the cost of transporting water back to the colony.

Antivirulence activity of azithromycin in Pseudomonas aeruginosa

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Francesco eImperi

2014-04-01

Full Text Available Antibiotics represent our bulwark to combat bacterial infections, but the spread of antibiotic resistance compromises their clinical efficacy. Alternatives to conventional antibiotics are urgently needed in order to complement the existing antibacterial arsenal. The macrolide antibiotic azithromycin (AZM provides a paradigmatic example of an unconventional antibacterial drug. Besides its growth-inhibiting activity, AZM displays potent anti-inflammatory properties, as well as antivirulence activity on some intrinsically resistant bacteria, such as Pseudomonas aeruginosa. In this bacterium, the antivirulence activity of AZM mainly relies on its ability to interact with the ribosome, resulting in direct and/or indirect repression of specific subsets of genes involved in virulence, quorum sensing, biofilm formation and intrinsic antibiotic resistance. Both clinical experience and clinical trials have shown the efficacy of AZM in the treatment of chronic pulmonary infections caused by P. aeruginosa. The aim of this review is to combine results from laboratory studies with evidence from clinical trials in order to unify the information on the in vivo mode of action of AZM in P. aeruginosa infection.

Cloning and Characterization of EF-Tu and EF-Ts from Pseudomonas aeruginosa

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Stephanie O. Palmer

2013-01-01

Full Text Available We have cloned genes encoding elongation factors EF-Tu and EF-Ts from Pseudomonas aeruginosa and expressed and purified the proteins to greater than 95% homogeneity. Sequence analysis indicated that P. aeruginosa EF-Tu and EF-Ts are 84% and 55% identical to E. coli counterparts, respectively. P. aeruginosa EF-Tu was active when assayed in GDP exchange assays. Kinetic parameters for the interaction of EF-Tu with GDP in the absence of EF-Ts were observed to be = 33 μM, = 0.003 s−1, and the specificity constant was  s−1 μM−1. In the presence of EF-Ts, these values were shifted to = 2 μM, = 0.005 s−1, and the specificity constant was  s−1 μM−1. The equilibrium dissociation constants governing the binding of EF-Tu to GDP ( were 30–75 nM and to GTP ( were 125–200 nM. EF-Ts stimulated the exchange of GDP by EF-Tu 10-fold. P. aeruginosa EF-Tu was active in forming a ternary complex with GTP and aminoacylated tRNA and was functional in poly(U-dependent binding of Phe-tRNAPhe at the A-site of P. aeruginosa ribosomes. P. aeruginosa EF-Tu was active in poly(U-programmed polyphenylalanine protein synthesis system composed of all P. aeruginosa components.

Polymorphonuclear leukocytes restrict growth of Pseudomonas aeruginosa in the lungs of cystic fibrosis patients

DEFF Research Database (Denmark)

Kragh, Kasper Nørskov; Alhede, Morten; Jensen, Peter Østrup

2014-01-01

Cystic fibrosis (CF) patients have increased susceptibility to chronic lung infections by Pseudomonas aeruginosa, but the ecophysiology within the CF lung during infections is poorly understood. The aim of this study was to elucidate the in vivo growth physiology of P. aeruginosa within lungs...... of chronically infected CF patients. A novel, quantitative peptide nucleic acid (PNA) fluorescence in situ hybridization (PNA-FISH)-based method was used to estimate the in vivo growth rates of P. aeruginosa directly in lung tissue samples from CF patients and the growth rates of P. aeruginosa in infected lungs...... in a mouse model. The growth rate of P. aeruginosa within CF lungs did not correlate with the dimensions of bacterial aggregates but showed an inverse correlation to the concentration of polymorphonuclear leukocytes (PMNs) surrounding the bacteria. A growth-limiting effect on P. aeruginosa by PMNs was also...

Extracellular DNA Shields against Aminoglycosides in Pseudomonas aeruginosa Biofilms

DEFF Research Database (Denmark)

Chiang, Wen-Chi; Nilsson, Martin; Jensen, Peter Østrup

2013-01-01

Within recent years, it has been established that extracellular DNA is a key constituent of the matrix of microbial biofilms. In addition, it has recently been demonstrated that DNA binds positively charged antimicrobials such as aminoglycosides and antimicrobial peptides. In the present study, we...... provide evidence that extracellular DNA shields against aminoglycosides in Pseudomonas aeruginosa biofilms. We show that exogenously supplemented DNA integrates into P. aeruginosa biofilms and increases their tolerance toward aminoglycosides. We provide evidence that biofilms formed by a DNA release......-deficient P. aeruginosa quorum-sensing mutant are more susceptible to aminoglycoside treatment than wild-type biofilms but become rescued from the detrimental action of aminoglycosides upon supplementation with exogenous DNA. Furthermore, we demonstrate that exposure to lysed polymorphonuclear leukocytes...

Evolution and adaptation of Pseudomonas aeruginosa in cystic fibrosis airways

DEFF Research Database (Denmark)

Madsen Sommer, Lea Mette

of natural environments, the primary obstacle is re-sampling of the samepopulation over time, especially if the population is small.Nevertheless, it has been accomplished: Chronic airway infections of cystic fibrosis (CF) patients have offered a unique view into the adaptationand evolution of Pseudomonas...... to the CF airways. From this analysis we found common clonal lineages among the patients, evidence of patient-to-patient transmission, historic contingencies, and convergent evolution of 52 candidate pathoadaptive genes. By further genome sequencing 26 P. aeruginosa isolates from four Italian CF patients...

Silver against Pseudomonas aeruginosa biofilms

DEFF Research Database (Denmark)

Bjarnsholt, Thomas; Kirketerp-Møller, K.; Kristiansen, S.

2007-01-01

bacteria in both the planktonic and biofilm modes of growth. The action of silver on mature in vitro biofilms of Pseudomonas aeruginosa, a primary pathogen of chronic infected wounds, was investigated. The results show that silver is very effective against mature biofilms of P. aeruginosa......, but that the silver concentration is important. A concentration of 5-10 ig/mL silver sulfadiazine eradicated the biofilm whereas a lower concentration (1 ig/mL) had no effect. The bactericidal concentration of silver required to eradicate the bacterial biofilm was 10-100 times higher than that used to eradicate...... planktonic bacteria. These observations strongly indicate that the concentration of silver in currently available wound dressings is much too low for treatment of chronic biofilm wounds. It is suggested that clinicians and manufacturers of the said wound dressings consider whether they are treating wounds...

Pseudomonas aeruginosa PA14 pathogenesis in Caenorhabditis elegans.

Science.gov (United States)

Kirienko, Natalia V; Cezairliyan, Brent O; Ausubel, Frederick M; Powell, Jennifer R

2014-01-01

The nematode Caenorhabditis elegans is a simple model host for studying the interaction between bacterial pathogens such as Pseudomonas aeruginosa and the metazoan innate immune system. Powerful genetic and molecular tools in both C. elegans and P. aeruginosa facilitate the identification and analysis of bacterial virulence factors as well as host defense factors. Here we describe three different assays that use the C. elegans-P. aeruginosa strain PA14 host-pathogen system. Fast Killing is a toxin-mediated death that depends on a diffusible toxin produced by PA14 but not on live bacteria. Slow Killing is due to an active infection in which bacteria colonize the C. elegans intestinal lumen. Liquid Killing is designed for high-throughput screening of chemical libraries for anti-infective compounds. Each assay has unique features and, interestingly, the PA14 virulence factors involved in killing are different in each assay.

RAPD- and ERIC-Based Typing of Clinical and Environmental Pseudomonas aeruginosa Isolates.

Science.gov (United States)

Auda, Ibtesam Ghadban; Al-Kadmy, Israa M S; Kareem, Sawsan Mohammed; Lafta, Aliaa Khyuon; A'Affus, Mustafa Hussein Obeid; Khit, Ibrahim Abd Aloahd; Al Kheraif, Abdulaziz Abdullah; Divakar, Darshan Devang; Ramakrishnaiah, Ravikumar

2017-03-01

Pseudomonas aeruginosa is a major cause of nosocomial infection in children and adults, resulting in significant morbidity and mortality due to its ability to acquire drug resistance. The ability of P. aeruginosa in the environment to cause infection in individuals has been reported previously; henceforth, surveillance of the emergence and transmission of P. aeruginosa strains among patients is important for infection control in a clinical setup. Various gene-typing methods have been used for epidemiological typing of P. aeruginosa isolates for the purpose of surveillance. In this work, the suitability and comparability of two typing methods, enterobacterial repetitive intergenic consensus (ERIC)-PCR and random amplification of polymorphic DNA (RAPD)-PCR fingerprinting, were studied to characterize P. aeruginosa strains isolated from clinical and environmental sources. Forty-four clinical and environmental bacterial isolates of P. aeruginosa were collected between October 2015 and January 2016. DNA extraction, ERIC-PCR and RAPD-PCR, agarose gel electrophoresis, and phylogenetic analyses were carried using the unweighted pair-group method with mean. RAPD typing revealed less clonality among clinical isolates, whereas the ERIC method showed greater similarity in comparison with RAPD. Environmental isolates, however, showed greater similarity using RAPD compared with ERIC typing. With only a few exceptions, most clinical isolates were distinct from environmental isolates, irrespective of the typing method. In conclusion, both the RAPD and ERIC typing methods proved to be good tools in understanding clonal diversity. The results also suggest that there is no relationship between clinical and environmental isolates. The absence of clonality among the clinical isolates may indicate that most P. aeruginosa infection cases could be endemic and not epidemic and that endemic infections may be due to nonclonal strains of P. aeruginosa.

Enterobactin-mediated iron transport in Pseudomonas aeruginosa.

Science.gov (United States)

Poole, K; Young, L; Neshat, S

1990-01-01

A pyoverdine-deficient strain of Pseudomonas aeruginosa was unable to grow in an iron-deficient minimal medium in the presence of the nonmetabolizable iron chelator ethylene diamine-di(omega-hydroxyphenol acetic acid) (EDDHA), although addition of enterobactin to EDDHA-containing minimal media did restore growth of the pyoverdine-deficient P. aeruginosa. Consistent with the apparent ability of enterobactin to provide iron to P. aeruginosa, enterobactin-dependent 55Fe3+ uptake was observed in cells of P. aeruginosa previously grown in an iron-deficient medium containing enterobactin (or enterobactin-containing Escherichia coli culture supernatant). This uptake was energy dependent, was observable at low concentrations (60 nM) of FeCl3, and was absent in cells cultured without enterobactin. A novel protein with a molecular weight of approximately 80,000 was identified in the outer membranes of cells grown in iron-deficient minimal medium containing enterobactin, concomitant with the induction of enterobactin-dependent iron uptake. A Tn501 insertion mutant lacking this protein was isolated and shown to be deficient in enterobactin-mediated iron transport at 60 nM FeCl3, although it still exhibited enterobactin-dependent growth in iron-deficient medium containing EDDHA. It was subsequently observed that the mutant was, however, capable of enterobactin-mediated iron transport at much higher concentrations (600 nM) of FeCl3. Indeed, enterobactin-dependent iron uptake at this concentration of iron was observed in both the mutant and parent strains irrespective of whether they had been cultured in the presence of enterobactin.(ABSTRACT TRUNCATED AT 250 WORDS) Images PMID:2174865

Ultraviolet-B lethal damage on Pseudomonas aeruginosa

International Nuclear Information System (INIS)

Degiorgi, C.F.; Fernandez, R.O.; Pizarro, R.A.

1996-01-01

Pseudomonas aeruginosa has shown an increased sensitivity compared with that of Escherichia coli and Enterobacter cloacae, when they were exposed to 0.4 kJ/m2 of ultraviolet-B radiation. The rapid decay in cell viability observed in Pseudomonas aeruginosa after the irradiation was influenced by factors such as culture media and the presence of pyocyanine during the irradiation. The radioinduced lethal damage could be prevented by photoreactivating treatment, indicating that pyrimidine dimer formation was the mechanism causing bacterial death. The results indicate that several environmental conditions may act as protective agents against ultraviolet-B-induced damage

Anaerobic Corrosion of 304 Stainless Steel Caused by the Pseudomonas aeruginosa Biofilm

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Ru Jia

2017-11-01

Full Text Available Pseudomonas aeruginosa is a ubiquitous bacterium capable of forming problematic biofilms in many environments. They cause biocorrosion of medical implants and industrial equipment and infrastructure. Aerobic corrosion of P. aeruginosa against stainless steels has been reported by some researchers while there is a lack of reports on anaerobic P. aeruginosa corrosion in the literature. In this work, the corrosion by a wild-type P. aeruginosa (strain PAO1 biofilm against 304 stainless steel (304 SS was investigated under strictly anaerobic condition for up to 14 days. The anaerobic corrosion of 304 SS by P. aeruginosa was reported for the first time. Results showed that the average sessile cell counts on 304 SS coupons after 7- and 14-day incubations were 4.8 × 107 and 6.2 × 107 cells/cm2, respectively. Scanning electron microscopy and confocal laser scanning microscopy corroborated the sessile cell counts. The X-ray diffraction analysis identified the corrosion product as iron nitride, confirming that the corrosion was caused by the nitrate reducing biofilm. The largest pit depths on 304 SS surfaces after the 7- and 14-day incubations with P. aeruginosa were 3.9 and 7.4 μm, respectively. Electrochemical tests corroborated the pitting data.

Attenuation of quorum-sensing-dependent virulence factors and biofilm formation by medicinal plants against antibiotic resistant Pseudomonas aeruginosa

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P. Sankar Ganesh

2018-01-01

Full Text Available Pseudomonas aeruginosa use small signaling molecules such as acyl homoserine lactones (AHLs, which play an important role in release virulence factors and toxin for further establishment of host infection. Thus, involving with the QS system would provide alternative ways of preventing the pathogenicity. In the present study, totally six medicinal plants (Terminalia bellerica, Celastrus paniculatus, Kingiodendron pinnatum, Schleichera oleosa, Melastoma malabathricum, Garcinia gummi-gutta were screened for anti-QS activity using biomonitor strain of Chromobacterium violaceum CV12472. The primary screening of antimicrobial activity of all the plant extracts have inhibited the growth of tested bacterial species. Of these at the sub-minimum inhibitory concentration the methanol extract of T. bellerica (0.0625–0.5 mg/ml has significantly inhibited violacein production (20.07–66.22% in C. violaceum (CV12472. Consequently, the extract of T. bellerica has reduced the production of pyocyanin, exopolysaccharide and biofilm formation in P. aeruginosa strains. Fluorescence and scanning electron microscopy analysis confirmed the reduction of biofilm formation in P. aeruginosa strains when treated with T. bellerica. GC–MS analysis showed the active compounds inhibited the production of virulence factors of P. aeruginosa. The results suggest the possible use of this T. bellerica as an anti-QS and anti-biofilm agent to control Pseudomonas infection. Interference of QS provides an important means for the inhibition of bacterial virulence and thus aids in treatment strategies.

Antibiotics Susceptibility Pattern of Pseudomonas aeruginosa ...

African Journals Online (AJOL)

ABSTRACT: This work investigated the prevalence and antibiotics sensitivity of Pseudomonas aeruginosa isolated from ... skin triggers coagulation and an acute inflammatory response ... agents with anti-pseudomonal activity, life-threatening.

[The effect of biyuanshu oral liquid on the formation of Pseudomonas aeruginosa biofilms in vitro].

Science.gov (United States)

Liu, Xiang; Chen, Haihong; Wang, Shengqing

2012-07-01

To observe the effect of biyuanshu oral liquid on the formation of pseudomonas aeruginosa biofilms in vitro. Pseudomonas aeruginosa biofilm was established by plate culture and detected by Scanning electron microscopy and AgNO3 staining. After treated with different dosages of biyuanshu oral liquid and erythromycin, the pseudomonas aeruginosa biofilms were observed by AgNO3 staining and the number of viable bacteria were measured by serial dilution. The pseudomonas aeruginosa biofilms could be detected by SEM at the seventh culture day and it was consistent with the detection of AgNO3 staining. The biyuanshu oral liquid and erythromycin have the effect on inhibiting the formation of pseudomonas aeruginosa biofilms. But with the already formed pseudomonas aeruginosa biofilms the inhibition was not significant. The serial dilution method showed that the viable counts of bacteria of biyuanshu oral liquid and erythromycin treated groups were significantly lower than those untreated groups (P formation of pseudomonas aeruginosa biofilms in vitro.

Interference of Pseudomonas aeruginosa signalling and biofilm formation for infection control

DEFF Research Database (Denmark)

Bjarnsholt, Thomas; Tolker-Nielsen, Tim; Høiby, Niels

2010-01-01

Pseudomonas aeruginosa is the best described bacterium with regards to quorum sensing (QS), in vitro biofilm formation and the development of antibiotic tolerance. Biofilms composed of P. aeruginosa are thought to be the underlying cause of many chronic infections, including those in wounds...... and in the lungs of patients with cystic fibrosis. In this review, we provide an overview of the molecular mechanisms involved in QS, QS-enabled virulence, biofilm formation and biofilm-enabled antibiotic tolerance. We now have substantial knowledge of the multicellular behaviour of P. aeruginosa in vitro. A major...

Virulence Genes Profile of Multidrug Resistant Pseudomonas aeruginosa Isolated from Iranian Children with UTIs

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Zohreh Heidary

2016-04-01

Full Text Available Virulent and resistant strains Pseudomonas aeruginosa (P. aeruginosa is one of the most important cause of UTIs in pediatrics. The present study was carried to investigate the frequency of virulence factors in the multi-drug resistant strains of P. aeruginosa isolated from pediatrics hospitalized due to the UTIs. One - hundred and forty three urine samples were collected from pediatric patients suffered from UTIs. Samples were cultured and those that were P. aeruginosa positive were analyzed for the presence of putative virulence genes. Seventy one out of 143 samples (49.65% were positive for P. aeruginosa. Monthly, sex and age-dependent prevalence were seen for P. aeruginosa. Bacterial strains had the highest levels of resistance against ampicillin (95.77%, gentamicin (92.95% and ciprofloxacin (81.69%. Of 71 P. aeruginosa isolates, 12 strains were resistant to more than 9 antibiotics (16.90%. The most commonly detected virulence factors in the cases of urethral infections were exoU and plcH while those of pyelonephritis and cystitis were were exoS and lasB. Our findings should raise awareness about antibiotic resistance in hospitalized pediatrics with UTIs in Iran. Clinicians should exercise caution in prescribing antibiotics, especially in cases of UTIs. Such information can help in identifying these virulence genes as useful diagnostic markers for clinical P. aeruginosa strains isolated from UTIs.

Cloning, Identification, and Characterization of the rpoS-Like Sigma Factor rpoX from Vibrio alginolyticus

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Jing-jing Zhao

2009-01-01

Full Text Available Vibrio alginolyticus ZJ-51 displays phase variation between opaque/rugose colonies (Op and translucent/smooth colonies (Tr. These colony variants show great differences in biofilm formation and motility. In this study, a gene encoding for an rpoS-like sigma factor, rpoX, has been cloned and characterized. The absence of rpoX did not affect colony switching rate but did decrease biofilm formation in both the Op and the Tr variants. When challenged with hydrogen peroxide, the ΔrpoX in the Op background showed a slightly higher survival rate compared with the wild type, whereas survival was decreased in the Tr background. Deletion of rpoX in the Tr background resulted in a higher ability to resist ethanol challenges and to survive hyperosmolarity challenges, and in the Op background the opposite phenotype was observed. This indicates that the rpoX gene is involved in biofilm formation and stress response but the effects are controlled by colony phase variation in V. alginolyticus.

Effects of antibiotics on quorum sensing in pseudomonas aeruginosa

DEFF Research Database (Denmark)

Skindersø, Mette Elena; Alhede, Morten; Phipps, Richard Kerry

2008-01-01

in animal infection models. Treatment of cystic fibrosis (CF) patients chronically infected with P. aeruginosa with the macrolide antibiotic azithromycin (AZM) has been demonstrated to improve the clinical outcome. Several studies indicate that AZM may accomplish its beneficial action in CF patients....... Three of the antibiotics tested, AZM, ceftazidime (CFT), and ciprofloxacin (CPR), were very active in the assay and were further examined for their effects on QS-regulated virulence factor production in P. aeruginosa. The effects of the three antibiotics administered at subinhibitory concentrations were...... by impeding QS, thereby reducing the pathogenicity of P. aeruginosa. This led us to investigate whether QS inhibition is a common feature of antibiotics. We present the results of a screening of 12 antibiotics for their QS-inhibitory activities using a previously described QS inhibitor selector 1 strain...

Outbreak of Pseudomonas aeruginosa bacteraemia in a haematology department

DEFF Research Database (Denmark)

Rasmussen, Benjamin Schnack; Christensen, Nikolas; Sørensen, Jan

2015-01-01

the outbreak and 12 months later. The audits were conducted by the method of direct observation. RESULTS: Several PFGE types were involved with no clear association to isolates from environmental samples. The audit revealed poor hygiene related to the handling of central venous catheters. After optimising......INTRODUCTION: Infection by Pseudomonas aeruginosa represents a major cause of morbidity and mortality among immunocompromised patients. In Denmark, an increase in P. aeruginosa isolates from blood cultures from a haematology department prompted a hygienic audit in 2007. METHODS: Blood cultures...... catheter hygiene, the number of P. aeruginosa bacteraemia cases fell significantly. CONCLUSION: Since no clear association between patient and environmental genotype was established, it was suspected that central venous catheters were the main portal of entry. This was further supported by a simultaneous...

Pseudomonas aeruginosa biofilms in the respiratory tract of cystic fibrosis patients

DEFF Research Database (Denmark)

Bjarnsholt, Thomas; Jensen, Peter Østrup; Fiandaca, Mark J

2009-01-01

therapy, explanted lungs from 3 intensively treated chronically P. aeruginosa infected CF patients and routine sputum from 77 chronically P. aeruginosa infected CF patients. All samples were investigated microscopically using hematoxylin-eosin (HE), Gram and alcian-blue stain, PNA FISH...

Human T cell colony formation in microculture: analysis of growth requirements and functional activities.

Science.gov (United States)

Gelfand, E W; Lee, J W; Dosch, H M; Price, G B

1981-03-01

A microculture method in methylcellulose has been developed for the study of human T cell colony formation. The technique is simple, reliable, does not require preincubation with lectin and requires small numbers of cells. Colony formation was dependent on the presence of phytohemagglutin-conditioned medium, a T colony precursor cell (TCPC), and a "helper" or accessory T cell. Plating efficiency was increased 10-fold in the presence of irradiated feeder cells. Progenitors of the T colony cells were identified in peripheral blood, tonsil, and spleen but not in thymus or thoracic duct. They were isolated in the E-rosetting, theophylline-resistant, Fc-IgG-negative cell populations. In peripheral blood the frequency of TCPC and accessory cells, the T colony forming unit, was estimated to be 8 X 10(-3). Colony cells proliferated in response to lectins and allogeneic cells. Forty to 80% of the cells were Ia-positive and stimulated both autologous and allogeneic mixed lymphocyte responses. They were incapable of mediating antibody-dependent cytotoxicity. In contrast, they were effective in assays of spontaneous cytotoxicity but only against certain target cells. This method for the analysis of T colony formation should prove valuable in the functional analysis of T cell subsets in immunodeficiency states or the transplant recipient.

Glycolipid-Dependent, Protease Sensitive Internalization of Pseudomonas aeruginosa Into Cultured Human Respiratory Epithelial Cells

Science.gov (United States)

Emam, Aufaugh; Carter, William G; Lingwood, Clifford

2010-01-01

Internalization of PAK strain Pseudomonas aeruginosa into human respiratory epithelial cell lines and HeLa cervical cancer cells in vitro was readily demonstrable via a gentamycin protection assay. Depletion of target cell glycosphingolipids (GSLs) using a glucosyl ceramide synthase inhibitor, P4, completely prevented P. aeruginosa internalization. In contrast, P4 treatment had no effect on the internalization of Salmonella typhimurium into HeLa cells. Internalized P. aeruginosa were within membrane vacuoles, often containing microvesicles, between the bacterium and the limiting membrane. P. aeruginosa internalization was markedly enhanced by target cell pretreatment with the exogenous GSL, deacetyl gangliotetraosyl ceramide (Gg4). Gg4 binds the lipid raft marker, GM1 ganglioside. Target cell pretreatment with TLCK, but not other (serine) protease inhibitors, prevented both P. aeruginosa host cell binding and internalization. NFkB inhibition also prevented internalization. A GSL-containing lipid-raft model of P. aeruginosa host cell binding/internalization is proposed PMID:21270937

Effects of hyperbaric oxygen on Pseudomonas aeruginosa susceptibility to imipenem and macrophages.

Science.gov (United States)

Lima, Flavia Luna; Joazeiro, Paulo Pinto; Lancellotti, Marcelo; de Hollanda, Luciana Maria; de Araújo Lima, Bruna; Linares, Edlaine; Augusto, Ohara; Brocchi, Marcelo; Giorgio, Selma

2015-01-01

The seriousness to treat burn wounds infected with Pseudomonas aeruginosa led us to examine whether the effect of the carbapenem antibiotic imipenem is enhanced by hyperbaric oxygen (HBO). The effects of HBO (100% O2, 3 ATA, 5 h) in combination with imipenen on bacterial counts of six isolates of P. aeruginosa and bacterial ultrastructure were investigated. Infected macrophages were exposed to HBO (100% O2, 3 ATA, 90 min) and the production of reactive oxygen species monitored. HBO enhanced the effects of imipenen. HBO increased superoxide anion production by macrophages and likely kills bacteria by oxidative mechanisms. HBO in combination with imipenem can be used to kill P. aeruginosa in vitro and such treatment may be beneficial for the patients with injuries containing the P. aeruginosa.

Seabird Colonies in Western Greenland

DEFF Research Database (Denmark)

Boertmann, D.; Mosbech, A.; Falk, K.

About 1 million seabirds (indvs) breed in 1032 colonies distributed along the coasts of western Greenland (Fig. 1). However, this figure does not include the little auk colonies in Avanersuaq. These colonies are roughly estimated to hold about 20 mill. pairs. All the basic information on seabird...... colonies in Greenland is compiled in a database maintained by NERI-AE. This report presents data on distribution, population numbers and population trends of 19 species of breeding colonial seabirds in western Greenland. Distributions are depicted on maps in Fig. 18-39. It is apparent that the major...... colonies are found in the northern part of the region, viz. Upernavik and Avanersuaq. The numbers of birds recorded in the database for each species are presented in Tab. 4, and on the basis of these figures estimates of the populations in western Greenland are given (Tab. 5). The most numerous species...

Within-host microevolution of Pseudomonas aeruginosa in Italian cystic fibrosis patients

DEFF Research Database (Denmark)

Marvig, Rasmus Lykke; Dolce, Daniela; Madsen Sommer, Lea Mette

2015-01-01

Chronic infection with Pseudomonas aeruginosa is a major cause of morbidity and mortality in cystic fibrosis (CF) patients, and a more complete understanding of P. aeruginosa within-host genomic evolution, transmission, and population genomics may provide a basis for improving intervention strate...

A Microfluidic Channel Method for Rapid Drug-Susceptibility Testing of Pseudomonas aeruginosa.

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Yoshimi Matsumoto

Full Text Available The recent global increase in the prevalence of antibiotic-resistant bacteria and lack of development of new therapeutic agents emphasize the importance of selecting appropriate antimicrobials for the treatment of infections. However, to date, the development of completely accelerated drug susceptibility testing methods has not been achieved despite the availability of a rapid identification method. We proposed an innovative rapid method for drug susceptibility testing for Pseudomonas aeruginosa that provides results within 3 h. The drug susceptibility testing microfluidic (DSTM device was prepared using soft lithography. It consisted of five sets of four microfluidic channels sharing one inlet slot, and the four channels are gathered in a small area, permitting simultaneous microscopic observation. Antimicrobials were pre-introduced into each channel and dried before use. Bacterial suspensions in cation-adjusted Mueller-Hinton broth were introduced from the inlet slot and incubated for 3 h. Susceptibilities were microscopically evaluated on the basis of differences in cell numbers and shapes between drug-treated and control cells, using dedicated software. The results of 101 clinically isolated strains of P. aeruginosa obtained using the DSTM method strongly correlated with results obtained using the ordinary microbroth dilution method. Ciprofloxacin, meropenem, ceftazidime, and piperacillin caused elongation in susceptible cells, while meropenem also induced spheroplast and bulge formation. Morphological observation could alternatively be used to determine the susceptibility of P. aeruginosa to these drugs, although amikacin had little effect on cell shape. The rapid determination of bacterial drug susceptibility using the DSTM method could also be applicable to other pathogenic species, and it could easily be introduced into clinical laboratories without the need for expensive instrumentation.

Intraspecific Variation among Social Insect Colonies: Persistent Regional and Colony-Level Differences in Fire Ant Foraging Behavior.

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Alison A Bockoven

Full Text Available Individuals vary within a species in many ecologically important ways, but the causes and consequences of such variation are often poorly understood. Foraging behavior is among the most profitable and risky activities in which organisms engage and is expected to be under strong selection. Among social insects there is evidence that within-colony variation in traits such as foraging behavior can increase colony fitness, but variation between colonies and the potential consequences of such variation are poorly documented. In this study, we tested natural populations of the red imported fire ant, Solenopsis invicta, for the existence of colony and regional variation in foraging behavior and tested the persistence of this variation over time and across foraging habitats. We also reared single-lineage colonies in standardized environments to explore the contribution of colony lineage. Fire ants from natural populations exhibited significant and persistent colony and regional-level variation in foraging behaviors such as extra-nest activity, exploration, and discovery of and recruitment to resources. Moreover, colony-level variation in extra-nest activity was significantly correlated with colony growth, suggesting that this variation has fitness consequences. Lineage of the colony had a significant effect on extra-nest activity and exploratory activity and explained approximately half of the variation observed in foraging behaviors, suggesting a heritable component to colony-level variation in behavior.

Rapid detection of Pseudomonas aeruginosa from positive blood cultures by quantitative PCR

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Cattoir Vincent

2010-08-01

Full Text Available Abstract Background Pseudomonas aeruginosa is responsible for numerous bloodstream infections associated with severe adverse outcomes in case of inappropriate initial antimicrobial therapy. The present study was aimed to develop a novel quantitative PCR (qPCR assay, using ecfX as the specific target gene, for the rapid and accurate identification of P. aeruginosa from positive blood cultures (BCs. Methods Over the period August 2008 to June 2009, 100 BC bottles positive for gram-negative bacilli were tested in order to evaluate performances of the qPCR technique with conventional methods as gold standard (i.e. culture and phenotypic identification. Results Thirty-three strains of P. aeruginosa, 53 strains of Enterobactericaeae, nine strains of Stenotrophomonas maltophilia and two other gram-negative species were isolated while 3 BCs were polymicrobial including one mixture containing P. aeruginosa. All P. aeruginosa clinical isolates were detected by qPCR except a single strain in mixed culture. Performances of the qPCR technique were: specificity, 100%; positive predictive value, 100%; negative predictive value, 98.5%; and sensitivity, 97%. Conclusions This reliable technique may offer a rapid (

Trehalose 6-phosphate phosphatases of Pseudomonas aeruginosa.

Science.gov (United States)

Cross, Megan; Biberacher, Sonja; Park, Suk-Youl; Rajan, Siji; Korhonen, Pasi; Gasser, Robin B; Kim, Jeong-Sun; Coster, Mark J; Hofmann, Andreas

2018-04-24

The opportunistic bacterium Pseudomonas aeruginosa has been recognized as an important pathogen of clinical relevance and is a leading cause of hospital-acquired infections. The presence of a glycolytic enzyme in Pseudomonas, which is known to be inhibited by trehalose 6-phosphate (T6P) in other organisms, suggests that these bacteria may be vulnerable to the detrimental effects of intracellular T6P accumulation. In the present study, we explored the structural and functional properties of trehalose 6-phosphate phosphatase (TPP) in P. aeruginosa in support of future target-based drug discovery. A survey of genomes revealed the existence of 2 TPP genes with either chromosomal or extrachromosomal location. Both TPPs were produced as recombinant proteins, and characterization of their enzymatic properties confirmed specific, magnesium-dependent catalytic hydrolysis of T6P. The 3-dimensional crystal structure of the chromosomal TPP revealed a protein dimer arising through β-sheet expansion of the individual monomers, which possess the overall fold of halo-acid dehydrogenases.-Cross, M., Biberacher, S., Park, S.-Y., Rajan, S., Korhonen, P., Gasser, R. B., Kim, J.-S., Coster, M. J., Hofmann, A. Trehalose 6-phosphate phosphatases of Pseudomonas aeruginosa.

Development of a Pseudomonas aeruginosa Agmatine Biosensor

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Adam Gilbertsen

2014-10-01

Full Text Available Agmatine, decarboxylated arginine, is an important intermediary in polyamine production for many prokaryotes, but serves higher functions in eukaryotes such as nitric oxide inhibition and roles in neurotransmission. Pseudomonas aeruginosa relies on the arginine decarboxylase and agmatine deiminase pathways to convert arginine into putrescine. One of the two known agmatine deiminase operons, aguBA, contains an agmatine sensitive TetR promoter controlled by AguR. We have discovered that this promoter element can produce a titratable induction of its gene products in response to agmatine, and utilized this discovery to make a luminescent agmatine biosensor in P. aeruginosa. The genome of the P. aeruginosa lab strain UCBPP-PA14 was altered to remove both its ability to synthesize or destroy agmatine, and insertion of the luminescent reporter construct allows it to produce light in proportion to the amount of exogenous agmatine applied from ~100 nM to 1mM. Furthermore it does not respond to related compounds including arginine or putrescine. To demonstrate potential applications the biosensor was used to detect agmatine in spent supernatants, to monitor the development of arginine decarboxylase over time, and to detect agmatine in the spinal cords of live mice.

Fate and effects of octylphenol in a Microcystis aeruginosa culture medium

International Nuclear Information System (INIS)

Baptista, Mafalda S.; Stoichev, Teodor; Basto, M. Clara P.; Vasconcelos, Vitor M.; Vasconcelos, M.Teresa S.D.

2009-01-01

Octylphenol (OP) is a xenobiotic with endocrine disrupting properties found in freshwaters worldwide. Its effects have been studied in organisms with nuclear receptors but effects on phytoplankton communities are poorly characterized, despite the fact that these organisms are constantly exposed to this compound. For this reason fate and effects of OP in the cyanobacterium Microcystis aeruginosa were assessed from 10 nM to 5 μM OP concentration. Up to a test concentration of 250 nM, OP removal increased significantly in the presence of cyanobacteria, the compound half-life in the absence of cells being 15 days against 9 days in the presence of the cells. Only 4% of the total OP removed was found bound to the cells, indicating an active metabolization of the compound. Moreover, the role of the exudates produced by M. aeruginosa, in the OP removal from culture medium, was assessed. Culture medium with exudates, resulting from a 7-day growth of M. aeruginosa, spiked with 50 nM OP, showed a higher half-life (22 days). Compared to culture medium without exudates, it can be hypothesized that higher organic matter concentrations make the hydrolysis or photolysis of OP more difficult. In culture media, the cells of M. aeruginosa could compensate and even counteract this, as OP half-life was shortened. At higher OP levels (1.25 and 5 μM) M. aeruginosa growth was impaired, indicating toxic effects. This shortage of biomass prevented the M. aeruginosa-assisted OP withdrawal from the culture media

Fate and effects of octylphenol in a Microcystis aeruginosa culture medium

Energy Technology Data Exchange (ETDEWEB)

Baptista, Mafalda S. [CIMAR/CIIMAR, Centro Interdisciplinar de Investigacao Marinha e Ambiental and FCUP, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal)], E-mail: abaptista@fc.up.pt; Stoichev, Teodor; Basto, M. Clara P.; Vasconcelos, Vitor M.; Vasconcelos, M.Teresa S.D. [CIMAR/CIIMAR, Centro Interdisciplinar de Investigacao Marinha e Ambiental and FCUP, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal)

2009-04-09

Octylphenol (OP) is a xenobiotic with endocrine disrupting properties found in freshwaters worldwide. Its effects have been studied in organisms with nuclear receptors but effects on phytoplankton communities are poorly characterized, despite the fact that these organisms are constantly exposed to this compound. For this reason fate and effects of OP in the cyanobacterium Microcystis aeruginosa were assessed from 10 nM to 5 {mu}M OP concentration. Up to a test concentration of 250 nM, OP removal increased significantly in the presence of cyanobacteria, the compound half-life in the absence of cells being 15 days against 9 days in the presence of the cells. Only 4% of the total OP removed was found bound to the cells, indicating an active metabolization of the compound. Moreover, the role of the exudates produced by M. aeruginosa, in the OP removal from culture medium, was assessed. Culture medium with exudates, resulting from a 7-day growth of M. aeruginosa, spiked with 50 nM OP, showed a higher half-life (22 days). Compared to culture medium without exudates, it can be hypothesized that higher organic matter concentrations make the hydrolysis or photolysis of OP more difficult. In culture media, the cells of M. aeruginosa could compensate and even counteract this, as OP half-life was shortened. At higher OP levels (1.25 and 5 {mu}M) M. aeruginosa growth was impaired, indicating toxic effects. This shortage of biomass prevented the M. aeruginosa-assisted OP withdrawal from the culture media.

Pseudomonas aeruginosa forms Biofilms in Acute InfectionIndependent of Cell-to-Cell Signaling

Energy Technology Data Exchange (ETDEWEB)

Schaber, J. Andy; Triffo, W.J.; Suh, Sang J.; Oliver, Jeffrey W.; Hastert, Mary C.; Griswold, John A.; Auer, Manfred; Hamood, Abdul N.; Rumbaugh, Kendra P.

2006-09-20

Biofilms are bacterial communities residing within a polysaccharide matrix that are associated with persistence and antibiotic resistance in chronic infections. We show that the opportunistic pathogen Pseudomonas aeruginosa forms biofilms within 8 hours of infection in thermally-injured mice, demonstrating that biofilms contribute to bacterial colonization in acute infections. P. aeruginosa biofilms were visualized within burned tissue surrounding blood vessels and adipose cells. Although quorum sensing (QS), a bacterial signaling mechanism, coordinates differentiation of biofilms in vitro, wild type and QS-deficient P. aeruginosa formed similar biofilms in vivo. Our findings demonstrate that P. aeruginosa forms biofilms on specific host tissues independent of QS.

Virus-Induced Type I Interferon Deteriorates Control of Systemic Pseudomonas Aeruginosa Infection

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Katja Merches

2015-07-01

Full Text Available Background: Type I interferon (IFN-I predisposes to bacterial superinfections, an important problem during viral infection or treatment with interferon-alpha (IFN-α. IFN-I-induced neutropenia is one reason for the impaired bacterial control; however there is evidence that more frequent bacterial infections during IFN-α-treatment occur independently of neutropenia. Methods: We analyzed in a mouse model, whether Pseudomonas aeruginosa control is influenced by co-infection with the lymphocytic choriomeningitis virus (LCMV. Bacterial titers, numbers of neutrophils and the gene-expression of liver-lysozyme-2 were determined during a 24 hours systemic infection with P. aeruginosa in wild-type and Ifnar-/- mice under the influence of LCMV or poly(I:C. Results: Virus-induced IFN-I impaired the control of Pseudomonas aeruginosa. This was associated with neutropenia and loss of lysozyme-2-expression in the liver, which had captured P. aeruginosa. A lower release of IFN-I by poly(I:C-injection also impaired the bacterial control in the liver and reduced the expression of liver-lysozyme-2. Low concentration of IFN-I after infection with a virulent strain of P. aeruginosa alone impaired the bacterial control and reduced lysozyme-2-expression in the liver as well. Conclusion: We found that during systemic infection with P. aeruginosa Kupffer cells quickly controlled the bacteria in cooperation with neutrophils. Upon LCMV-infection this cooperation was disturbed.

Interactions between Microcystis aeruginosa and coexisting amoxicillin contaminant at different phosphorus levels.

Science.gov (United States)

Liu, Ying; Chen, Shi; Chen, Xiao; Zhang, Jian; Gao, Baoyu

2015-10-30

Microcystis aeruginosa was cultured with 0.05-5 mg L(-1) of phosphorus and exposed to 200-500 ng L(-1) of amoxicillin for seven days. Amoxicillin presented no significant effect (p>0.05) on the growth of M. aeruginosa at phosphorus levels of 0.05 and 0.2 mg L(-1), but stimulated algal growth as a hormesis effect at phosphorus levels of 1 and 5 mg L(-1). Phosphorus and amoxicillin affected the contents of chlorophyll-a, adenosine triphosphate (ATP) and malondialdehyde, the expression of psbA and rbcL, as well as the activities of adenosinetriphosphatase and glutathione S-transferase in similar manners, but regulated the production and release of microcystins and the activities of superoxide dismutase and peroxidase in different ways. Increased photosynthesis activity was related with the ATP consumption for the stress response to amoxicillin, and the stress response was enhanced as the phosphorus concentration increased. The biodegradation of amoxicillin by M. aeruginosa increased from 11.5% to 28.2% as the phosphorus concentration increased. Coexisting amoxicillin aggravated M. aeruginosa pollution by increasing cell density and concentration of microcystins, while M. aeruginosa alleviated amoxicillin pollution via biodegradation. The interactions between M. aeruginosa and amoxicillin were significantly regulated by phosphorus (p<0.05) and led to a complicated situation of combined pollution. Copyright © 2015 Elsevier B.V. All rights reserved.

2-Aminoacetophenone as a potential breath biomarker for Pseudomonas aeruginosa in the cystic fibrosis lung

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Laing Richard

2010-11-01

Full Text Available Abstract Background Pseudomonas aeruginosa infections are associated with progressive life threatening decline of lung function in cystic fibrosis sufferers. Growth of Ps. aeruginosa releases a "grape-like" odour that has been identified as the microbial volatile organic compound 2-aminoacetophenone (2-AA. Methods We investigated 2-AA for its specificity to Ps. aeruginosa and its suitability as a potential breath biomarker of colonisation or infection by Solid Phase Micro Extraction and Gas Chromatography-Mass Spectrometry (GC/MS. Results Cultures of 20 clinical strains of Ps. aeruginosa but not other respiratory pathogens had high concentrations of 2-AA in the head space of in vitro cultures when analysed by GC/MS. 2-AA was stable for 6 hours in deactivated glass sampling bulbs but was not stable in Tedlar® bags. Optimisation of GC/MS allowed detection levels of 2-AA to low pico mol/mol range in breath. The 2-AA was detected in a significantly higher proportion of subjects colonised with Ps. aeruginosa 15/16 (93.7% than both the healthy controls 5/17 (29% (p Ps. aeruginosa 4/13(30.7% (p Ps. aeruginosa in sputum and/or BALF was 93.8% (95% CI, 67-99 and 69.2% (95% CI, 38-89 respectively. The peak integration values for 2-AA analysis in the breath samples were significantly higher in Ps. aeruginosa colonised subjects (median 242, range 0-1243 than the healthy controls (median 0, range 0-161; p Ps. aeruginosa (median 0, range 0-287; p Conclusions Our results report 2-AA as a promising breath biomarker for the detection of Ps. aeruginosa infections in the cystic fibrosis lung.

Inhibition of Pseudomonas aeruginosa elastase and Pseudomonas keratitis using a thiol-based peptide.

OpenAIRE

Burns, F R; Paterson, C A; Gray, R D; Wells, J T

1990-01-01

Pseudomonas aeruginosa elastase is a zinc metalloproteinase which is released during P. aeruginosa infections. Pseudomonas keratitis, which occurs following contact lens-induced corneal trauma, can lead to rapid, liquefactive necrosis of the cornea. This destruction has been attributed to the release of both host-derived enzymes and the bacterial products P. aeruginosa elastase, alkaline protease, exotoxin A, and lipopolysaccharide endotoxin. A synthetic metalloproteinase inhibitor, HSCH2 (DL...

Polysaccharides serve as scaffold of biofilms formed by mucoid Pseudomonas aeruginosa

DEFF Research Database (Denmark)

Yang, Liang; Hengzhuang, Wang; Wu, Hong

2012-01-01

Chronic lung infection by mucoid Pseudomonas aeruginosa is one of the major pathologic features in patients with cystic fibrosis. Mucoid P. aeruginosa is notorious for its biofilm forming capability and resistance to immune attacks. In this study, the roles of extracellular polymeric substances f...

Spatial heterogeneity as a genetic mixing mechanism in highly philopatric colonial seabirds.

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Cristofari, Robin; Trucchi, Emiliano; Whittington, Jason D; Vigetta, Stéphanie; Gachot-Neveu, Hélène; Stenseth, Nils Christian; Le Maho, Yvon; Le Bohec, Céline

2015-01-01

How genetic diversity is maintained in philopatric colonial systems remains unclear, and understanding the dynamic balance of philopatry and dispersal at all spatial scales is essential to the study of the evolution of coloniality. In the King penguin, Aptenodytes patagonicus, return rates of post-fledging chicks to their natal sub-colony are remarkably high. Empirical studies have shown that adults return year after year to their previous breeding territories within a radius of a few meters. Yet, little reliable data are available on intra- and inter-colonial dispersal in this species. Here, we present the first fine-scale study of the genetic structure in a king penguin colony in the Crozet Archipelago. Samples were collected from individual chicks and analysed at 8 microsatellite loci. Precise geolocation data of hatching sites and selective pressures associated with habitat features were recorded for all sampling locations. We found that despite strong natal and breeding site fidelity, king penguins retain a high degree of panmixia and genetic diversity. Yet, genetic structure appears markedly heterogeneous across the colony, with higher-than-expected inbreeding levels, and local inbreeding and relatedness hotspots that overlap predicted higher-quality nesting locations. This points towards heterogeneous population structure at the sub-colony level, in which fine-scale environmental features drive local philopatric behaviour, while lower-quality patches may act as genetic mixing mechanisms at the colony level. These findings show how a lack of global genetic structuring can emerge from small-scale heterogeneity in ecological parameters, as opposed to the classical model of homogeneous dispersal. Our results also emphasize the importance of sampling design for estimation of population parameters in colonial seabirds, as at high spatial resolution, basic genetic features are shown to be location-dependent. Finally, this study stresses the importance of

Spatial heterogeneity as a genetic mixing mechanism in highly philopatric colonial seabirds.

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Robin Cristofari

Full Text Available How genetic diversity is maintained in philopatric colonial systems remains unclear, and understanding the dynamic balance of philopatry and dispersal at all spatial scales is essential to the study of the evolution of coloniality. In the King penguin, Aptenodytes patagonicus, return rates of post-fledging chicks to their natal sub-colony are remarkably high. Empirical studies have shown that adults return year after year to their previous breeding territories within a radius of a few meters. Yet, little reliable data are available on intra- and inter-colonial dispersal in this species. Here, we present the first fine-scale study of the genetic structure in a king penguin colony in the Crozet Archipelago. Samples were collected from individual chicks and analysed at 8 microsatellite loci. Precise geolocation data of hatching sites and selective pressures associated with habitat features were recorded for all sampling locations. We found that despite strong natal and breeding site fidelity, king penguins retain a high degree of panmixia and genetic diversity. Yet, genetic structure appears markedly heterogeneous across the colony, with higher-than-expected inbreeding levels, and local inbreeding and relatedness hotspots that overlap predicted higher-quality nesting locations. This points towards heterogeneous population structure at the sub-colony level, in which fine-scale environmental features drive local philopatric behaviour, while lower-quality patches may act as genetic mixing mechanisms at the colony level. These findings show how a lack of global genetic structuring can emerge from small-scale heterogeneity in ecological parameters, as opposed to the classical model of homogeneous dispersal. Our results also emphasize the importance of sampling design for estimation of population parameters in colonial seabirds, as at high spatial resolution, basic genetic features are shown to be location-dependent. Finally, this study stresses the

Application of bacteriophages to selectively remove Pseudomonas aeruginosa in water and wastewater filtration systems.

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Zhang, Yanyan; Hunt, Heather K; Hu, Zhiqiang

2013-09-01

Water and wastewater filtration systems often house pathogenic bacteria, which must be removed to ensure clean, safe water. Here, we determine the persistence of the model bacterium Pseudomonas aeruginosa in two types of filtration systems, and use P. aeruginosa bacteriophages to determine their ability to selectively remove P. aeruginosa. These systems used beds of either anthracite or granular activated carbon (GAC), which were operated at an empty bed contact time (EBCT) of 45 min. The clean bed filtration systems were loaded with an instantaneous dose of P. aeruginosa at a total cell number of 2.3 (± 0.1 [standard deviation]) × 10(7) cells. An immediate dose of P. aeruginosa phages (1 mL of phage stock at the concentration of 2.7 × 10(7) PFU (Plaque Forming Units)/mL) resulted in a reduction of 50% (± 9%) and >99.9% in the effluent P. aeruginosa concentrations in the clean anthracite and GAC filters, respectively. To further evaluate the effects of P. aeruginosa phages, synthetic stormwater was run through anthracite and GAC biofilters where mixed-culture biofilms were present. Eighty five days after an instantaneous dose of P. aeruginosa (2.3 × 10(7) cells per filter) on day 1, 7.5 (± 2.8) × 10(7) and 1.1 (± 0.5) × 10(7) P. aeruginosa cells/g filter media were detected in the top layer (close to the influent port) of the anthracite and GAC biofilters, respectively, demonstrating the growth and persistence of pathogenic bacteria in the biofilters. A subsequent 1-h dose of phages, at the concentration of 5.1 × 10(6) PFU/mL and flow rate of 1.6 mL/min, removed the P. aeruginosa inside the GAC biofilters and the anthracite biofilters by 70% (± 5%) and 56% (± 1%), respectively, with no P. aeruginosa detected in the effluent, while not affecting ammonia oxidation or the ammonia-oxidizing bacterial community inside the biofilters. These results suggest that phage treatment can selectively remove pathogenic bacteria with minimal impact on beneficial

Swimming Motility Mediates the Formation of Neutrophil Extracellular Traps Induced by Flagellated Pseudomonas aeruginosa.

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Madison Floyd

2016-11-01

Full Text Available Pseudomonas aeruginosa is an opportunistic pathogen causing severe infections often characterized by robust neutrophilic infiltration. Neutrophils provide the first line of defense against P. aeruginosa. Aside from their defense conferred by phagocytic activity, neutrophils also release neutrophil extracellular traps (NETs to immobilize bacteria. Although NET formation is an important antimicrobial process, the details of its mechanism are largely unknown. The identity of the main components of P. aeruginosa responsible for triggering NET formation is unclear. In this study, our focus was to identify the main bacterial factors mediating NET formation and to gain insight into the underlying mechanism. We found that P. aeruginosa in its exponential growth phase promoted strong NET formation in human neutrophils while its NET-inducing ability dramatically decreased at later stages of bacterial growth. We identified the flagellum as the primary component of P. aeruginosa responsible for inducing NET extrusion as flagellum-deficient bacteria remained seriously impaired in triggering NET formation. Purified P. aeruginosa flagellin, the monomeric component of the flagellum, does not stimulate NET formation in human neutrophils. P. aeruginosa-induced NET formation is independent of the flagellum-sensing receptors TLR5 and NLRC4 in both human and mouse neutrophils. Interestingly, we found that flagellar motility, not flagellum binding to neutrophils per se, mediates NET release induced by flagellated bacteria. Immotile, flagellar motor-deficient bacterial strains producing paralyzed flagella did not induce NET formation. Forced contact between immotile P. aeruginosa and neutrophils restored their NET-inducing ability. Both the motAB and motCD genetic loci encoding flagellar motor genes contribute to maximal NET release; however the motCD genes play a more important role. Phagocytosis of P. aeruginosa and superoxide production by neutrophils were also

Association, roost use and simulated disruption of Myotis septentrionalis maternity colonies

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Silvis, Alexander; Ford, W. Mark; Britzke, Eric R.; Johnson, Joshua B.

2014-01-01

How wildlife social and resource networks are distributed on the landscape and how animals respond to resource loss are important aspects of behavioral ecology. For bats, understanding these responses may improve conservation efforts and provide insights into adaptations to environmental conditions. We tracked maternity colonies of northern bats (Myotis septentrionalis) at Fort Knox, Kentucky, USA to evaluate their social and resource networks and space use. Roost and social network structure differed between maternity colonies. Overall roost availability did not appear to be strongly related to network characteristics or space use. In simulations for our two largest networks, roost removal was related linearly to network fragmentation; despite this, networks were relatively robust, requiring removal of >20% of roosts to cause network fragmentation. Results from our analyses indicate that northern bat behavior and space use may differ among colonies and potentially across the maternity season. Simulation results suggest that colony social structure is robust to fragmentation caused by random loss of small numbers of roosts. Flexible social dynamics and tolerance of roost loss may be adaptive strategies for coping with ephemeral conditions in dynamic forest habitats.

Kant's Second Thoughts on Colonialism

NARCIS (Netherlands)

Kleingeld, Pauline; Flikschuh, Katrin; Ypi, Lea

2014-01-01

Kant is widely regarded as a fierce critic of colonialism. In Toward Perpetual Peace and the Metaphysics of Morals, for example, he forcefully condemns European conduct in the colonies as a flagrant violation of the principles of right. His earlier views on colonialism have not yet received much

Caracterización, por RAPD-PCR, de aislados de Pseudomonas aeruginosa obtenidos de pacientes con fibrosis quística RAPD-PCR characterization of Pseudomonas aeruginosa strains obtained from cystic fibrosis patients

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Maribel Ortiz-Herrera

2004-04-01

Full Text Available OBJETIVO: Caracterizar a las cepas de P aeruginosa aisladas de lavados broncoalveolares de pacientes con fibrosis quística a lo largo de un periodo de tres años. MATERIAL Y MÉTODOS: Estudio prospectivo, de seguimiento de una población de pacientes con fibrosis quística. Se utilizó la técnica de la amplificación del ADN empleando PCR con bajas condiciones de especificidad (Random amplified polymorphic DNA, RAPD-PCR para la amplificación del ADN de cepas de P aeruginosa aisladas de lavados broncoalveolares de cinco pacientes con fibrosis quística, provenientes del Servicio de Neumología y Cirugía del Tórax del Instituto Nacional de Pediatría de la Ciudad de México, en el periodo de junio de 1996 a junio de 2002; se establecieron los patrones de amplificación de cada aislamiento, lo que permitió la identificación precisa de todas las cepas aisladas y el estudio de la epidemiología de P aeruginosa en los pacientes seleccionados con dicha enfermedad. RESULTADOS: Se definieron 18 patrones de amplificación del ADN que permitieron identificar a cada cepa de P aeruginosa aislada en las diferentes muestras de lavado broncoalveolar; no se encontró relación entre el fenotipo de P aeruginosa (mucoide o no mucoide y el genotipo de cada aislamiento, ya que cepas con fenotipos distintos mostraron patrones de amplificación semejantes; en nuestros pacientes se identificaron cepas con patrones de amplificación distintos a partir de una misma muestra, lo que sugiere la presencia de infecciones simultáneas por más de una cepa de P aeruginosa; se demostró que dos hermanos con la enfermedad compartían cepas con genotipos semejantes, lo que sugiere una contaminación cruzada entre ambos, y se demostró el aislamiento de cepas de P aeruginosa con genotipos semejantes a lo largo de los periodos estudiados. CONCLUSIONES: La identificación mediante la caracterización genotípica de las cepas de P aeruginosa aisladas de los pacientes con

Behavioral Modulation of Infestation by Varroa destructor in Bee Colonies. Implications for Colony Stability.

Science.gov (United States)

de Figueiró Santos, Joyce; Coelho, Flávio Codeço; Bliman, Pierre-Alexandre

2016-01-01

Colony Collapse Disorder (CCD) has become a global problem for beekeepers and for the crops that depend on bee pollination. While many factors are known to increase the risk of colony collapse, the ectoparasitic mite Varroa destructor is considered to be the most serious one. Although this mite is unlikely to cause the collapse of hives itself, it is the vector for many viral diseases which are among the likely causes for Colony Collapse Disorder. The effects of V. destructor infestation differ from one part of the world to another, with greater morbidity and higher colony losses in European honey bees (EHB) in Europe, Asia and North America. Although this mite has been present in Brazil for many years, there have been no reports of colony losses amongst Africanized Honey Bees (AHB). Studies carried out in Mexico have highlighted different behavioral responses by the AHB to the presence of the mite, notably as far as grooming and hygienic behavior are concerned. Could these explain why the AHB are less susceptible to Colony Collapse Disorder? In order to answer this question, we have developed a mathematical model of the infestation dynamics to analyze the role of resistance behavior by bees in the overall health of the colony, and as a consequence, its ability to face epidemiological challenges.

Behavioral Modulation of Infestation by Varroa destructor in Bee Colonies. Implications for Colony Stability.

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Joyce de Figueiró Santos

Full Text Available Colony Collapse Disorder (CCD has become a global problem for beekeepers and for the crops that depend on bee pollination. While many factors are known to increase the risk of colony collapse, the ectoparasitic mite Varroa destructor is considered to be the most serious one. Although this mite is unlikely to cause the collapse of hives itself, it is the vector for many viral diseases which are among the likely causes for Colony Collapse Disorder. The effects of V. destructor infestation differ from one part of the world to another, with greater morbidity and higher colony losses in European honey bees (EHB in Europe, Asia and North America. Although this mite has been present in Brazil for many years, there have been no reports of colony losses amongst Africanized Honey Bees (AHB. Studies carried out in Mexico have highlighted different behavioral responses by the AHB to the presence of the mite, notably as far as grooming and hygienic behavior are concerned. Could these explain why the AHB are less susceptible to Colony Collapse Disorder? In order to answer this question, we have developed a mathematical model of the infestation dynamics to analyze the role of resistance behavior by bees in the overall health of the colony, and as a consequence, its ability to face epidemiological challenges.

Colonialism, customary law and the post-colonial state in Africa: the ...

African Journals Online (AJOL)

Colonialism became a fact of life in many African countries. An effect of colonialism especially in the former British colonized countries was the transplantation of the British legal system, which led to recognition of both systems and the gradual relegation of the indigenous system otherwise called customary law. The use and ...

Public Heath in Colonial and Post-Colonial Ghana: Lesson-Drawing for The Twenty-First Century

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Adu-Gyamfi, Samuel

2017-06-01

Full Text Available Public health in twenty-first century Ghana is mired with several issues ranging from the inadequacy of public health facilities, improper settlement planning, insanitary conditions, and the inadequacy of laws and their implementation. This situation compared to the colonial era is a direct contradiction. Development in the pre-colonial era to the colonial era sought to make the prevention of diseases a priority in the colonial administration. This was begun with the establishment of the health branch in 1909 as a response to the bubonic plague that was fast spreading in the colony. From here public health policies and strategies were enacted to help the diseases prevention cause. Various public health boards, the medical research institute or the laboratory branch, the waste management department, the use of preventive medicine and maintenance of good settlement planning and sanitation were public health measures in the colonial era. This research seeks to analyse the public health system in the colonial era so as to draw basic lessons for twenty-first century Ghana. Archival data and other secondary sources are reviewed and analysed to help draw these lessons. Richard Rose’s lesson-drawing approach was used to draw the lessons.

Pseudomonas aeruginosa biofilms in cystic fibrosis

DEFF Research Database (Denmark)

Høiby, Niels; Ciofu, Oana; Bjarnsholt, Thomas

2010-01-01

The persistence of chronic Pseudomonas aeruginosa lung infections in cystic fibrosis (CF) patients is due to biofilm-growing mucoid (alginate-producing) strains. A biofilm is a structured consortium of bacteria, embedded in a self-produced polymer matrix consisting of polysaccharide, protein...... and DNA. In CF lungs, the polysaccharide alginate is the major part of the P. aeruginosa biofilm matrix. Bacterial biofilms cause chronic infections because they show increased tolerance to antibiotics and resist phagocytosis, as well as other components of the innate and the adaptive immune system....... As a consequence, a pronounced antibody response develops, leading to immune complex-mediated chronic inflammation, dominated by polymorphonuclear leukocytes. The chronic inflammation is the major cause of the lung tissue damage in CF. Biofilm growth in CF lungs is associated with an increased frequency...

A case of failed eradication of cystic fibrosis-related sinus colonisation by Pseudomonas aeruginosa.

LENUS (Irish Health Repository)

Linnane, Barry

2015-10-01

Pseudomonas aeruginosa is a pathogen associated with cystic fibrosis that has potential to decrease lung function and cause respiratory failure. Paranasal sinuses are increasingly recognised as potential reservoirs for intermittent colonisation by P. aeruginosa. This case documents investigation and outcome of P. aeruginosa recurrence in a male paediatric patient over an eight year period.

Pseudomonas aeruginosa in Swimming Pool Water: Evidences and Perspectives for a New Control Strategy

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Marco Guida

2016-09-01

Full Text Available Pseudomonas aeruginosa is frequently isolated in swimming pool settings. Nine recreational and rehabilitative swimming pools were monitored according to the local legislation. The presence of P. aeruginosa was correlated to chlorine concentration. The ability of the isolates to form a biofilm on plastic materials was also investigated. In 59.5% of the samples, microbial contamination exceeded the threshold values. P. aeruginosa was isolated in 50.8% of these samples. The presence of P. aeruginosa was not correlated with free or total chlorine amount (R2 < 0.1. All the isolates were moderate- to strong-forming biofilm (Optical Density O.D.570 range 0.7–1.2. To control biofilm formation and P. aeruginosa colonization, Quantum FreeBioEnergy© (QFBE, FreeBioEnergy, Brisighella, Italy, has been applied with encouraging preliminary results. It is a new, promising control strategy based on the change of an electromagnetic field which is responsible for the proliferation of some microorganisms involved in biofilm formation, such as P. aeruginosa.

Only Acyl Carrier Protein 1 (AcpP1 Functions in Pseudomonas aeruginosa Fatty Acid Synthesis

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Jin-Cheng Ma

2017-11-01

Full Text Available The genome of Pseudomonas aeruginosa contains three open reading frames, PA2966, PA1869, and PA3334, which encode putative acyl carrier proteins, AcpP1, AcpP2, and AcpP3, respectively. In this study, we found that, although these apo-ACPs were successfully phosphopantetheinylated by P. aeruginosa phosphopantetheinyl transferase (PcpS and all holo-forms of these proteins could be acylated by Vibrio harveyi acyl-ACP synthetase (AasS, only AcpP1 could be used as a substrate for the synthesis of fatty acids, catalyzed by P. aeruginosa cell free extracts in vitro, and only acpP1 gene could restore growth in the Escherichia coliacpP mutant strain CY1877. And P. aeruginosaacpP1 could not be deleted, while disruption of acpP2 or acpP3 in the P. aeruginosa genome allowed mutant strains to grow as well as the wild type strain. These findings confirmed that only P. aeruginosa AcpP1 functions in fatty acid biosynthesis, and that acpP2 and acpP3 do not play roles in the fatty acid synthetic pathway. Moreover, disruption of acpP2 and acpP3 did not affect the ability of P. aeruginosa to produce N-acylhomoserine lactones (AHL, but replacement of P. aeruginosaacpP1 with E. coliacpP caused P. aeruginosa to reduce the production of AHL molecules, which indicated that neither P. aeruginosa AcpP2 nor AcpP3 can act as a substrate for synthesis of AHL molecules in vivo. Furthermore, replacement of acpP1 with E. coliacpP reduced the ability of P. aeruginosa to produce some exo-products and abolished swarming motility in P. aeruginosa.

SuhB Is a Regulator of Multiple Virulence Genes and Essential for Pathogenesis of Pseudomonas aeruginosa

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Li, Kewei; Xu, Chang; Jin, Yongxin; Sun, Ziyu; Liu, Chang; Shi, Jing; Chen, Gukui; Chen, Ronghao; Jin, Shouguang; Wu, Weihui

2013-01-01

ABSTRACT During initial colonization and chronic infection, pathogenic bacteria encounter distinct host environments. Adjusting gene expression accordingly is essential for the pathogenesis. Pseudomonas aeruginosa has evolved complicated regulatory networks to regulate different sets of virulence factors to facilitate colonization and persistence. The type III secretion system (T3SS) and motility are associated with acute infections, while biofilm formation and the type VI secretion system (T6SS) are associated with chronic persistence. To identify novel regulatory genes required for pathogenesis, we screened a P. aeruginosa transposon (Tn) insertion library and found suhB to be an essential gene for the T3SS gene expression. The expression of suhB was upregulated in a mouse acute lung infection model, and loss of suhB resulted in avirulence. Suppression of T3SS gene expression in the suhB mutant is linked to a defective translation of the T3SS master regulator, ExsA. Further studies demonstrated that suhB mutation led to the upregulation of GacA and its downstream small RNAs, RsmY and RsmZ, triggering T6SS expression and biofilm formation while inhibiting the T3SS. Our results demonstrate that an in vivo-inducible gene, suhB, reciprocally regulates genes associated with acute and chronic infections and plays an essential role in the pathogenesis of P. aeruginosa. PMID:24169572

Inhibitory effects of sanguinarine against the cyanobacterium Microcystis aeruginosa NIES-843 and possible mechanisms of action

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Shao, Jihai [College of Resources and Environment, Hunan Agricultural University, Changsha 410128 (China); Hunan Provincial Key Laboratory of Farmland Pollution Control and Agricultural Resources Use, Hunan Agricultural University, Changsha 410128 (China); Liu, Deming [State Key Laboratory Breeding Base of Crop Germplasm Innovation and Resource Utilization, Hunan Agricultural University, Changsha 410128 (China); Gong, Daoxin; Zeng, Qingru; Yan, Zhiyong [College of Resources and Environment, Hunan Agricultural University, Changsha 410128 (China); Gu, Ji-Dong, E-mail: jdgu@hku.hk [Hunan Provincial Key Laboratory of Farmland Pollution Control and Agricultural Resources Use, Hunan Agricultural University, Changsha 410128 (China); Laboratory of Environmental Microbiology and Toxicology, School of Biological Sciences, The University of Hong Kong, Hong Kong SAR (China)

2013-10-15

Highlights: •Sanguinarine was found as a strong algicidal biologically derived substance. •Sanguinarine can induce oxidative stress in the cells of Microcystis aeruginosa. •Photosystem is a target of toxicity of sanguinarine on M. aeruginosa. •Sanguinarine can induce DNA damage and inhibit cell division. -- Abstract: Sanguinarine showed strong inhibitory effect against Microcystis aeruginosa, a typical water bloom-forming and microcystins-producing cyanobacterium. The EC50 of sanguinarine against the growth of M. aeruginosa NIES-843 was 34.54 ± 1.17 μg/L. Results of chlorophyll fluorescence transient analysis indicated that all the electron donating side, accepting side, and the reaction center of the Photosystem II (PS II) were the targets of sanguinarine against M. aeruginosa NIES-843. The elevation of reactive oxygen species (ROS) level in the cells of M. aeruginosa NIES-843 upon exposure indicated that sanguinarine induced oxidative stress in the active growing cells of M. aeruginosa NIES-843. Further results of gene expression analysis indicated that DNA damage and cell division inhibition were also involved in the inhibitory action mechanism of sanguinarine against M. aeruginosa NIES-843. The inhibitory characteristics of sanguinarine against M. aeruginosa suggest that the ecological- and public health-risks need to be evaluated before its application in cyanobacterial bloom control to avoid devastating events irreversibly.

Análise epidemiológica de isolados clínicos de Pseudomonas aeruginosa provenientes de hospital universitário Epidemiologic analysis of clinical isolates of Pseudomonas aeruginosa from an university hospital

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Eduardo José Valença Cordeiro Pires

2009-12-01

Full Text Available OBJETIVOS: A Pseudomonas aeruginosa é um patógeno oportunista que tem se destacado quanto à prevalência em casos de infecções hospitalares. Sua ampla resistência aos diversos grupos de antimicrobianos garante a este microrganismo um papel de destaque entre as bactérias mais prevalentes associadas à infecção nosocomial. O objetivo deste estudo foi realizar um levantamento epidemiológico da P. aeruginosa, bem como do seu perfil de susceptibilidade aos antimicrobianos no Hospital das Clínicas da Universidade Federal de Pernambuco. MÉTODOS: Foi realizado um estudo retrospectivo baseado no livro de registro de secreções diversas do laboratório de bacteriologia do Hospital das Clínicas no período compreendido entre janeiro a junho de 2008. Entre os registros, identificamos aqueles que foram positivos para a P. aeruginosa, analisando sua origem e perfil de susceptibilidade aos antimicrobianos utilizados na rotina daquele laboratório. RESULTADOS: As bactérias mais freqüentes, isoladas das secreções diversas, foram P. aeruginosa (26% e S. aureus (25%. Quanto à origem, a P. aeruginosa foi isolada principalmente de infecções respiratórias, pois 33% das amostras positivas para esta bactéria foram provinientes de secreções traqueais e 21% nasais. Os antimicrobianos mais eficazes contra a P. aeruginosa foram: amicacina, imipenem, meropenem e aztreonam. CONCLUSÕES: Estes resultados mostram uma alta prevalência de P. aeruginosa, no Hospital das Clínicas da Universidade Federal de Pernambuco. Apesar de apresentar grande resistência a antimicrobianos mais antigos como as cefalosporinas de primeira e segunda geração, assim como cloranfenicol, em geral, este patógeno demonstrou boa sensibilidade às drogas utilizadas na rotina deste hospital.OBJECTIVES: Pseudomonas aeruginosa is an increasingly prevalent opportunistic pathogen in hospital infection cases. Its high resistance rates to many antimicrobials has given this

[Effect of Pseudomonas aeruginosa exometabolites on planktonic and biofilm cultures of Escherichia coli].

Science.gov (United States)

Kuznetsova, M V; Karpunina, T I; Maslennikova, I L; Nesterova, L Iu; Demakov, V A

2012-01-01

Study the effect of P. aeruginosa exometabolites on planktonic and biofilm cultures of bioluminescent E. coli strain. E. coli K12 TG1 (pF1 lux+ Ap(r)) recombinant bioluminescent strain, P. aeruginosa ATCC 27853 reference strain and 2 nosocomial isolates were used. Pyocyanin and pyoverdin content in supernatant of P. aeruginosa over-night cultures was evaluated according to E. Deziel et al. (2001). Planktonic and biofilm cultures of E. coli were obtained in 96-well plates (LB, statically, 37 degrees C), optical density of plankton, film biomass (OD600, OD580) and bioluminescence in plankton and biofilm were evaluated in microplate reader Infiniti M200 (Tecan, Austria). P. aeruginosa exometabolites increased the duration of lag-phase in E. coli, and short term exposition inhibited luminescence of planktonic cells. These effects are determined by bactericidal action ofpyocyanin and pyoverdin. Supernatants ofover-night cultures of P. aeruginosa inhibit formation of biofilm and disrupt the formed biofilm of E. coli. Effect of pyocyanin and pyoverdin on these processes is not established, other factors may have higher significance. Bioluminescence of E. coli K12 TGI that reflects the energetic status of the cell allows to evaluate and prognose the character of coexistence of P. aeruginosa in combined with E. coli planktonic and biofilm culture.

Pseudomonas cepacia adherence to respiratory epithelial cells is enhanced by Pseudomonas aeruginosa

International Nuclear Information System (INIS)

Saiman, L.; Cacalano, G.; Prince, A.

1990-01-01

Pseudomonas aeruginosa and Pseudomonas cepacia are both opportunistic pathogens of patients with cystic fibrosis. The binding characteristics of these two species were compared to determine if they use similar mechanisms to adhere to respiratory epithelial cells. P. cepacia 249 was shown to be piliated, but there was no detectable homology between P. aeruginosa pilin gene probes and P. cepacia genomic DNA. P. cepacia and P. aeruginosa did not appear to compete for epithelial receptors. In the presence of purified P. aeruginosa pili, the adherence of 35S-labeled strain 249 to respiratory epithelial monolayers was unaffected, while that of P. aeruginosa PAO1 was decreased by 55%. The binding of P. cepacia 249 and 715j was increased by 2.4-fold and 1.5-fold, respectively, in the presence of an equal inoculum of PAO1. Interbacterial agglutination contributed to the increased adherence of P. cepacia, as the binding of 249 was increased twofold in the presence of irradiated PAO1. PAO1 exoproducts had a marked effect in enhancing the ability of the P. cepacia strains to adhere to the epithelial monolayers. A PAO1 supernatant increased the binding of 249 by eightfold and that of 715j by fourfold. Thus, there appears to be a synergistic relationship between P. aeruginosa and P. cepacia in which PAO1 exoproducts modify the epithelial cell surface, exposing receptors and facilitating increased P. cepacia attachment

A Novel Insight into Dehydroleucodine Mediated Attenuation of Pseudomonas aeruginosa Virulence Mechanism

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S. Mustafi

2015-01-01

Full Text Available Increasing resistance of Pseudomonas aeruginosa (P. aeruginosa to conventional treatments demands the search for novel therapeutic strategies. In this study, the antimicrobial activity of dehydroleucodine (DhL, a sesquiterpene lactone obtained from Artemisia (A. douglasiana, was screened against several pathogenic virulence effectors of P. aeruginosa. In vitro, minimum inhibitory concentration of DhL was determined against P. aeruginosa strains PAO1, PA103, PA14, and multidrug resistant clinical strain, CDN118. Results showed that DhL was active against each strain where PAO1 and PA103 showed higher susceptibility (MIC 0.48 mg/mL as compared to PA14 (MIC 0.96 mg/mL and CDN118 (MIC 0.98 mg/mL. Also, when PAO1 strain was grown in the presence of DhL (MIC50, 0.12 mg/mL, a delay in the generation time was noticed along with significant inhibition of secretory protease and elastase activities, interruption in biofilm attachment phase in a stationary culture, and a significant decline in Type III effector ExoS. At MIC50, DhL treatment increased the sensitivity of P. aeruginosa towards potent antibiotics. Furthermore, treatment of P. aeruginosa with DhL prevented toxin-induced apoptosis in macrophages. These observations suggest that DhL activity was at the bacterial transcriptional level. Hence, antimicrobial activity of DhL may serve as leads in the development of new anti-Pseudomonas pharmaceuticals.

Pseudomonas aeruginosa ExoU augments neutrophil transepithelial migration.

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Pazos, Michael A; Lanter, Bernard B; Yonker, Lael M; Eaton, Alex D; Pirzai, Waheed; Gronert, Karsten; Bonventre, Joseph V; Hurley, Bryan P

2017-08-01

Excessive neutrophil infiltration of the lungs is a common contributor to immune-related pathology in many pulmonary disease states. In response to pathogenic infection, airway epithelial cells produce hepoxilin A3 (HXA3), initiating neutrophil transepithelial migration. Migrated neutrophils amplify this recruitment by producing a secondary gradient of leukotriene B4 (LTB4). We sought to determine whether this two-step eicosanoid chemoattractant mechanism could be exploited by the pathogen Pseudomonas aeruginosa. ExoU, a P. aeruginosa cytotoxin, exhibits phospholipase A2 (PLA2) activity in eukaryotic hosts, an enzyme critical for generation of certain eicosanoids. Using in vitro and in vivo models of neutrophil transepithelial migration, we evaluated the impact of ExoU expression on eicosanoid generation and function. We conclude that ExoU, by virtue of its PLA2 activity, augments and compensates for endogenous host neutrophil cPLA2α function, leading to enhanced transepithelial migration. This suggests that ExoU expression in P. aeruginosa can circumvent immune regulation at key signaling checkpoints in the neutrophil, resulting in exacerbated neutrophil recruitment.

Pseudomonas aeruginosa ExoU augments neutrophil transepithelial migration.

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Michael A Pazos

2017-08-01

Full Text Available Excessive neutrophil infiltration of the lungs is a common contributor to immune-related pathology in many pulmonary disease states. In response to pathogenic infection, airway epithelial cells produce hepoxilin A3 (HXA3, initiating neutrophil transepithelial migration. Migrated neutrophils amplify this recruitment by producing a secondary gradient of leukotriene B4 (LTB4. We sought to determine whether this two-step eicosanoid chemoattractant mechanism could be exploited by the pathogen Pseudomonas aeruginosa. ExoU, a P. aeruginosa cytotoxin, exhibits phospholipase A2 (PLA2 activity in eukaryotic hosts, an enzyme critical for generation of certain eicosanoids. Using in vitro and in vivo models of neutrophil transepithelial migration, we evaluated the impact of ExoU expression on eicosanoid generation and function. We conclude that ExoU, by virtue of its PLA2 activity, augments and compensates for endogenous host neutrophil cPLA2α function, leading to enhanced transepithelial migration. This suggests that ExoU expression in P. aeruginosa can circumvent immune regulation at key signaling checkpoints in the neutrophil, resulting in exacerbated neutrophil recruitment.

Direct evaluation of Pseudomonas aeruginosa biofilm mediators in a chronic infection model.

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Byrd, Matthew S; Pang, Bing; Hong, Wenzhou; Waligora, Elizabeth A; Juneau, Richard A; Armbruster, Chelsie E; Weimer, Kristen E D; Murrah, Kyle; Mann, Ethan E; Lu, Haiping; Sprinkle, April; Parsek, Matthew R; Kock, Nancy D; Wozniak, Daniel J; Swords, W Edward

2011-08-01

Biofilms contribute to Pseudomonas aeruginosa persistence in a variety of diseases, including cystic fibrosis, burn wounds, and chronic suppurative otitis media. However, few studies have directly addressed P. aeruginosa biofilms in vivo. We used a chinchilla model of otitis media, which has previously been used to study persistent Streptococcus pneumoniae and Haemophilus influenzae infections, to show that structures formed in vivo are biofilms of bacterial and host origin within a matrix that includes Psl, a P. aeruginosa biofilm polysaccharide. We evaluated three biofilm and/or virulence mediators of P. aeruginosa known to affect biofilm formation in vitro and pathogenesis in vivo--bis-(3',5')-cyclic dimeric GMP (c-di-GMP), flagella, and quorum sensing--in a chinchilla model. We show that c-di-GMP overproduction has a positive impact on bacterial persistence, while quorum sensing increases virulence. We found no difference in persistence attributed to flagella. We conclude from these studies that a chinchilla otitis media model provides a means to evaluate pathogenic mediators of P. aeruginosa and that in vitro phenotypes should be examined in multiple infection systems to fully understand their role in disease.

Pseudomonas aeruginosa Biofilm, a Programmed Bacterial Life for Fitness.

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Lee, Keehoon; Yoon, Sang Sun

2017-06-28

A biofilm is a community of microbes that typically inhabit on surfaces and are encased in an extracellular matrix. Biofilms display very dissimilar characteristics to their planktonic counterparts. Biofilms are ubiquitous in the environment and influence our lives tremendously in both positive and negative ways. Pseudomonas aeruginosa is a bacterium known to produce robust biofilms. P. aeruginosa biofilms cause severe problems in immunocompromised patients, including those with cystic fibrosis or wound infection. Moreover, the unique biofilm properties further complicate the eradication of the biofilm infection, leading to the development of chronic infections. In this review, we discuss the history of biofilm research and general characteristics of bacterial biofilms. Then, distinct features pertaining to each stage of P. aeruginosa biofilm development are highlighted. Furthermore, infections caused by biofilms on their own or in association with other bacterial species ( i.e. , multispecies biofilms) are discussed in detail.

Necrotizing Pseudomonas aeruginosa Community-Acquired Pneumonia: A Case Report and Review of the Literature

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Satish Maharaj

2017-01-01

Full Text Available Lung cavities are not typically associated with community-acquired pneumonia (CAP. CAP due to P. aeruginosa is rare and even less commonly causes necrotizing pneumonia. We report a case of P. aeruginosa CAP that progressed to necrotizing pneumonia and was eventually fatal. Procalcitonin (PCT has been well investigated in guiding antibiotic therapy (especially CAP in adults. In this case, PCT at presentation and sequentially was negative. We discuss this caveat and present hypotheses as to the sensitivity and specificity of PCT and C-reactive protein (CRP in these patients. To better characterize P. aeruginosa CAP, we undertook a review of cases indexed in PubMed from 2001 to 2016 (n=9. The data reveal that risk factors for P. aeruginosa CAP include smoking, alcohol use, obstructive lung disease, sinusitis, and hot tub use. The route of infection for P. aeruginosa CAP remains unknown. One of the most interesting findings on reviewing cases was that P. aeruginosa CAP involves the right upper lobe in the vast majority. We suggest that when physicians in the community see patients with distinctly upper lobe necrotizing or cavitary pneumonia, they should consider P. aeruginosa in their differential diagnosis. Further studies are needed to clarify route of infection, role of PCT and CRP, and optimal therapy including drug and duration.

Dynamics of the Presence of Israeli Acute Paralysis Virus in Honey Bee Colonies with Colony Collapse Disorder

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Chunsheng Hou

2014-05-01

Full Text Available The determinants of Colony Collapse Disorder (CCD, a particular case of collapse of honey bee colonies, are still unresolved. Viruses including the Israeli acute paralysis virus (IAPV were associated with CCD. We found an apiary with colonies showing typical CCD characteristics that bore high loads of IAPV, recovered some colonies from collapse and tested the hypothesis if IAPV was actively replicating in them and infectious to healthy bees. We found that IAPV was the dominant pathogen and it replicated actively in the colonies: viral titers decreased from April to September and increased from September to December. IAPV extracted from infected bees was highly infectious to healthy pupae: they showed several-fold amplification of the viral genome and synthesis of the virion protein VP3. The health of recovered colonies was seriously compromised. Interestingly, a rise of IAPV genomic copies in two colonies coincided with their subsequent collapse. Our results do not imply IAPV as the cause of CCD but indicate that once acquired and induced to replication it acts as an infectious factor that affects the health of the colonies and may determine their survival. This is the first follow up outside the US of CCD-colonies bearing IAPV under natural conditions.

Pseudomonas aeruginosa endophthalmitis masquerading as chronic uveitis

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Kalpana Badami Nagaraj

2013-01-01

Full Text Available A 65-year-old male presented with decreased vision in the left eye of 15-day duration after having undergone an uneventful cataract surgery 10 months back. He had been previously treated with systemic steroids for recurrent uveitis postoperatively on three occasions in the same eye. B-scan ultrasonography showed multiple clumplike echoes suggestive of vitreous inflammation. Aqueous tap revealed Pseudomonas aeruginosa sensitive to ciprofloxacin. The patient was treated with intravitreal ciprofloxacin and vancomycin along with systemic ciprofloxacin with good clinical response. Even a virulent organism such as P.aeruginosa can present as a chronic uveitis, which, if missed, can lead to a delay in accurate diagnosis and appropriate management.

Pseudomonas aeruginosa (Family Pseudomonadaceae) is an ...

African Journals Online (AJOL)

Pseudomonas aeruginosa (Family Pseudomonadaceae) is an obligate aerobic, motile, gram negative bacillus.which is able to grow and survive in almost any environment and resistant to temperature extremes. It is involved in the etiology of several diseases i.

Lipopolysaccharides of the cyanobacterium Microcystis aeruginosa

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Raziuddin, S.; Siegelman, H.W.; Tornabene, T.G.

1983-01-01

Lipopolysaccharides (LPS) of two isolates of Microcystis aeruginosa were extracted with phenol/water and purified. Cesium chloride gradient ultracentrifugation of these preparations yielded only one fraction. The LPS contained significant amounts of 3-deoxy-D-manno-octulosonic acid, glucose, 3-deoxy sugars, glucosamine, fatty acids, fatty acid esters, hexoses, and phosphate. Heptose, a characteristic sugar component of the polysaccharide moiety of LPS of most gram-negative bacteria was absent. Lipopolysaccharides and lipid A hydrolysate of LPS preparations were active in mouse lethality and Limulus lysate gelation. The lipid A moiety was slightly less active in toxicity and Limulus lysate gelation assay than the intact LPS. The LPS and lipid A moiety of the two isolates of M. aeruginosa were less active in toxicity in mice and Limulus test than LPS of Salmonella abortus equi. 37 references, 1 figure, 3 tables.

Bead-size directed distribution of Pseudomonas aeruginosa results in distinct inflammatory response in a mouse model of chronic lung infection

DEFF Research Database (Denmark)

Christophersen, L J; Trøstrup, H; Damlund, Dina Silke Malling

2012-01-01

or in the peripheral respiratory zone. To study this we produced two distinct sizes of small alginate beads (SB) and large beads (LB) containing P. aeruginosa. In total, 175 BALB/c mice were infected with either SB or LB. At day 1 the quantitative bacteriology was higher in the SB group compared to the LB group (P

Tolerance of Pseudomonas aeruginosa in in-vitro biofilms to high-level peracetic acid disinfection.

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Akinbobola, A B; Sherry, L; Mckay, W G; Ramage, G; Williams, C

2017-10-01

Biofilm has been suggested as a cause of disinfection failures in flexible endoscopes where no lapses in the decontamination procedure can be identified. To test this theory, the activity of peracetic acid, one of the widely used disinfectants in the reprocessing of flexible endoscopes, was evaluated against both planktonic and sessile communities of Pseudomonas aeruginosa. To investigate the ability of P. aeruginosa biofilm to survive high-level peracetic acid disinfection. The susceptibility of planktonic cells of P. aeruginosa and biofilms aged 24, 48, 96, and 192 h to peracetic acid was evaluated by estimating their viability using resazurin viability and plate count methods. The biomass of the P. aeruginosa biofilms was also quantified using Crystal Violet assay. Planktonic cells of P. aeruginosa were treated with 5-30 ppm concentration of peracetic acid in the presence of 3.0 g/L of bovine serum albumin (BSA) for 5 min. Biofilms of P. aeruginosa were also treated with various peracetic acid concentrations (100-3000 ppm) for 5 min. Planktonic cells of P. aeruginosa were eradicated by 20 ppm of peracetic acid, whereas biofilms showed an age-dependent tolerance to peracetic acid, and 96 h biofilm was only eradicated at peracetic acid concentration of 2500 ppm. Ninety-six-hour P. aeruginosa biofilm survives 5 min treatment with 2000 ppm of peracetic acid, which is the working concentration used in some endoscope washer-disinfectors. This implies that disinfection failure of flexible endoscopes might occur when biofilms build up in the lumens of endoscopes. Copyright © 2017. Published by Elsevier Ltd.

Comparative In Vitro Efficacy of Doripenem and Imipenem Against Multi-Drug Resistant Pseudomonas aeruginosa

International Nuclear Information System (INIS)

Wali, N.; Mirza, I. A.

2016-01-01

Objective: To compare the in vitro efficacy of doripenem and imipenem against multi-drug resistant (MDR) Pseudomonas aeruginosa from various clinical specimens. Study Design: Descriptive cross-sectional study. Place and Duration of Study: Department of Microbiology, Armed Forces Institute of Pathology, Rawalpindi, from November 2012 to November 2013. Methodology: MDR Pseudomonas aeruginosa isolates from various clinical samples were included in the study. Susceptibility of Pseudomonas aeruginosa against doripenem and imipenem was performed by E-test strip and agar dilution methods. The results were interpreted as recommended by Clinical Laboratory Standard Institute (CLSI) guidelines. Results: The maximum number of Pseudomonas aeruginosa were isolated from pure pus and pus swabs. In vitro efficacy of doripenem was found to be more effective as compared to imipenem against MDR Pseudomonas aeruginosa with both E-test strip and agar dilution methods. Overall, p-values of 0.014 and 0.037 were observed when susceptibility patterns of doripenem and imipenem were evaluated with E-test strip and agar dilution methods. Conclusion: In vitro efficacy of doripenem was found to be better against MDR Pseudomonas aeruginosa as compared to imipenem when tested by both E-test and agar dilution methods. (author)

Strain- and Substrate-Dependent Redox Mediator and Electricity Production by Pseudomonas aeruginosa.

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Bosire, Erick M; Blank, Lars M; Rosenbaum, Miriam A

2016-08-15

Pseudomonas aeruginosa is an important, thriving member of microbial communities of microbial bioelectrochemical systems (BES) through the production of versatile phenazine redox mediators. Pure culture experiments with a model strain revealed synergistic interactions of P. aeruginosa with fermenting microorganisms whereby the synergism was mediated through the shared fermentation product 2,3-butanediol. Our work here shows that the behavior and efficiency of P. aeruginosa in mediated current production is strongly dependent on the strain of P. aeruginosa We compared levels of phenazine production by the previously investigated model strain P. aeruginosa PA14, the alternative model strain P. aeruginosa PAO1, and the BES isolate Pseudomonas sp. strain KRP1 with glucose and the fermentation products 2,3-butanediol and ethanol as carbon substrates. We found significant differences in substrate-dependent phenazine production and resulting anodic current generation for the three strains, with the BES isolate KRP1 being overall the best current producer and showing the highest electrochemical activity with glucose as a substrate (19 μA cm(-2) with ∼150 μg ml(-1) phenazine carboxylic acid as a redox mediator). Surprisingly, P. aeruginosa PAO1 showed very low phenazine production and electrochemical activity under all tested conditions. Microbial fuel cells and other microbial bioelectrochemical systems hold great promise for environmental technologies such as wastewater treatment and bioremediation. While there is much emphasis on the development of materials and devices to realize such systems, the investigation and a deeper understanding of the underlying microbiology and ecology are lagging behind. Physiological investigations focus on microorganisms exhibiting direct electron transfer in pure culture systems. Meanwhile, mediated electron transfer with natural redox compounds produced by, for example, Pseudomonas aeruginosa might enable an entire microbial

Glycan involvement in the adhesion of Pseudomonas aeruginosa to tears.

Science.gov (United States)

Kautto, Liisa; Nguyen-Khuong, Terry; Everest-Dass, Arun; Leong, Andrea; Zhao, Zhenjun; Willcox, Mark D P; Packer, Nicolle H; Peterson, Robyn

2016-04-01

The human eye is constantly bathed by tears, which protect the ocular surface via a variety of mechanisms. The O-linked glycans of tear mucins have long been considered to play a role in binding to pathogens and facilitating their removal in the tear flow. Other conjugated glycans in tears could similarly contribute to pathogen binding and removal but have received less attention. In the work presented here we assessed the contribution of glycan moieties, in particular the protein attached N-glycans, presented by the broad complement of tear proteins to the adhesion of the opportunistic pathogen Pseudomonas aeruginosa, a leading cause of microbial keratitis and ulceration of the cornea. Our adhesion assay involved immobilising the macromolecular components of tears into the wells of a polyvinyl difluoride (PVDF) microtitre filter plate and probing the binding of fluorescently labelled bacteria. Three P. aeruginosa strains were studied: a cytotoxic strain (6206) and an invasive strain (6294) from eye infections, and an invasive strain (320) from a urinary tract infection (UTI). The ocular isolates adhered two to three times more to human tears than to human saliva or porcine gastric mucin, suggesting ocular niche-specific adaptation. Support for the role of the N-glycans carried by human tear proteins in the binding and removal of P. aeruginosa from the eye was shown by: 1) pre-incubation of the bacteria with free component sugars, galactose, mannose, fucose and sialyl lactose (or combination thereof) inhibiting adhesion of all the P. aeruginosa strains to the immobilised tear proteins, with the greatest inhibition of binding of the ocular cytotoxic 6206 and least for the invasive 6294 strain; 2) pre-incubation of the bacteria with N-glycans released from the commercially available human milk lactoferrin, an abundant protein that carries N-linked glycans in tears, inhibiting the adhesion to tears of the ocular bacteria by up to 70%, which was significantly more

Pseudomonas aeruginosa multiresistente em unidade de cuidados intensivos: desafios que procedem? Pseudomonas aeruginosa multiresistente en una unidad de cuidados intensivos: desafíos que proceden? Multi-resistant pseudomonas aeruginosa among patients from an intensive care unit: persistent challenge?

Directory of Open Access Journals (Sweden)

Maria Verônica Guilherme Ferrareze

2007-03-01

Full Text Available OBJETIVOS: Avaliar a ocorrência de infecção hospitalar por Pseudomonas aeruginosa multiresistente em pacientes hospitalizados em uma unidade de cuidados intensivos. MÉTODO: estudo retrospectivo realizado de outubro de 2003 a setembro de 2004 em um hospital de emergências. RESULTADOS: Totalizou-se 68 portadores de bactérias multiresistentes sendo 10 (14,7% de P. aeruginosa. Destes, 8 pacientes eram do sexo masculino, as médias de idade e de internação foram respectivamente de 57 anos a média de idade, 43,7 a média de dias de internação e 7 pacientes morreram. Isolaram-se 8 cepas no sangue, cinco na urina, duas em cateteres venosos e uma no líquor, das quais sete sensíveis somente a polimixina e três ao imipenem. CONCLUSÃO: O perfil microbiológico deve ser avaliado periodicamente visto que é específico de uma unidade ou instituição, e demanda ações correlatas.OBJETIVOS: Evaluar la ocurrencia de infección hospitalaria por Pseudomonas aeruginosa multiresistente en pacientes hospitalizados en una unidad de cuidados intensivos. MÉTODO: estudio retrospectivo realizado de octubre del 2003 a setiembre del 2004 en un hospital de emergencias. RESULTADOS: Se tuvo un total de 68 portadores de bacterias multiresistentes de las cuales 10 (14,7% de P. aeruginosa. De éstos, 8 pacientes eran del sexo masculino, los promedios de edad y de internamiento fueron respectivamente de 57 años y 43,7 de días de internamiento y 7 pacientes murieron. Se aislaron 8 cepas en la sangre, cinco en la orina, dos en catéteres venosos y una en el licor, de ellas siete eran sensibles sólo a la polimixina y tres al imipenem. CONCLUSIÓN: El perfil microbiológico debe ser evaluado periódicamente dado que es específico de una unidad o institución, y demanda acciones correlatas.OBJECTIVES: To evaluate the occurrence of multi-resistant Pseudomonas Aeruginosa infection among patients from an Intensive Care Unit. METHODS: This retrospective study was

Growth Mechanism of Microbial Colonies

Science.gov (United States)

Zhu, Minhui; Martini, K. Michael; Kim, Neil H.; Sherer, Nicholas; Lee, Jia Gloria; Kuhlman, Thomas; Goldenfeld, Nigel

Experiments on nutrient-limited E. coli colonies, growing on agar gel from single cells reveal a power-law distribution of sizes, both during the growth process and in the final stage when growth has ceased. We developed a Python simulation to study the growth mechanism of the bacterial population and thus understand the broad details of the experimental findings. The simulation takes into account nutrient uptake, metabolic function, growth and cell division. Bacteria are modeled in two dimensions as hard circle-capped cylinders with steric interactions and elastic stress dependent growth characteristics. Nutrient is able to diffuse within and between the colonies. The mechanism of microbial colony growth involves reproduction of cells within the colonies and the merging of different colonies. We report results on the dynamic scaling laws and final state size distribution, that capture in semi-quantitative detail the trends observed in experiment. Supported by NSF Grant 0822613.

Molecular Epidemiology of a Pseudomonas aeruginosa Hospital Outbreak Driven by a Contaminated Disinfectant-Soap Dispenser

Science.gov (United States)

Lanini, Simone; D'Arezzo, Silvia; Puro, Vincenzo; Martini, Lorena; Imperi, Francesco; Piselli, Pierluca; Montanaro, Marco; Paoletti, Simonetta; Visca, Paolo; Ippolito, Giuseppe

2011-01-01

Background and Objective Pseudomonas aeruginosa infection represents a main cause of morbidity and mortality among immunocompromised patients. This study describes a fatal epidemic of P. aeruginosa that occurred in a hematology unit in Italy. Methods Retrospective cohort study, prospective surveillance, auditing, extensive testing on healthcare workers and environmental investigation were performed to define the dynamics and potential causes of transmission. RAPD, macrorestriction analyses and sequence typing were used to define relationships between P. aeruginosa isolates. Results Eighteen cases of infection were identified in the different phases of the investigation. Of these, five constitute a significant molecular cluster of infection. A P. aeruginosa strain with the same genetic fingerprint and sequence type (ST175) as clinical isolates strain was also isolated from a heavily contaminated triclosan soap dispenser. Discussion and Conclusions Our results are consistent with the hypothesis that patients became indirectly infected, e.g., during central venous catheter handling through contaminated items, and that the triclosan soap dispenser acted as a common continuous source of P. aeruginosa infection. Since P. aeruginosa is intrinsically unsusceptible to triclosan, the use of triclosan-based disinfectant formulations should be avoided in those healthcare settings hosting patients at high risk of P. aeruginosa infection. PMID:21359222

Pollen foraging in colonies of Melipona bicolor (Apidae, Meliponini): effects of season, colony size and queen number.

Science.gov (United States)

Hilário, S D; Imperatriz-Fonseca, V L

2009-01-01

We evaluated the ratio between the number of pollen foragers and the total number of bees entering colonies of Melipona bicolor, a facultative polygynous species of stingless bees. The variables considered in our analysis were: seasonality, colony size and the number of physogastric queens in each colony. The pollen forager ratios varied significantly between seasons; the ratio was higher in winter than in summer. However, colony size and number of queens per colony had no significant effect. We conclude that seasonal differences in pollen harvest are related to the production of sexuals and to the number of individuals and their body size.

Use of model plant hosts to identify Pseudomonas aeruginosa virulence factors

Science.gov (United States)

Rahme, Laurence G.; Tan, Man-Wah; Le, Long; Wong, Sandy M.; Tompkins, Ronald G.; Calderwood, Stephen B.; Ausubel, Frederick M.

1997-01-01

We used plants as an in vivo pathogenesis model for the identification of virulence factors of the human opportunistic pathogen Pseudomonas aeruginosa. Nine of nine TnphoA mutant derivatives of P. aeruginosa strain UCBPP-PA14 that were identified in a plant leaf assay for less pathogenic mutants also exhibited significantly reduced pathogenicity in a burned mouse pathogenicity model, suggesting that P. aeruginosa utilizes common strategies to infect both hosts. Seven of these nine mutants contain TnphoA insertions in previously unknown genes. These results demonstrate that an alternative nonvertebrate host of a human bacterial pathogen can be used in an in vivo high throughput screen to identify novel bacterial virulence factors involved in mammalian pathogenesis. PMID:9371831

Regulation and function of versatile aerobic and anaerobic respiratory metabolism in Pseudomonas aeruginosa

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Hiroyuki eArai

2011-05-01

Full Text Available Pseudomonas aeruginosa is a ubiquitously distributed opportunistic pathogen that inhabits soil and water as well as animal-, human-, and plant-host-associated environments. The ubiquity would be attributed to its very versatile energy metabolism. P. aeruginosa has a highly branched respiratory chain terminated by multiple terminal oxidases and denitrification enzymes. Five terminal oxidases for aerobic respiration have been identified in the P. aeruginosa cells. Three of them, the cbb3-1 oxidase, the cbb3-2 oxidase, and the aa3 oxidase, are cytochrome c oxidases and the other two, the bo3 oxidase and the cyanide-insensitive oxidase, are quinol oxidases. Each oxidase has a specific affinity for oxygen, efficiency of energy coupling, and tolerance to various stresses such as cyanide and reactive nitrogen species. These terminal oxidases are used differentially according to the environmental conditions. P. aeruginosa also has a complete set of the denitrification enzymes that reduce nitrate to molecular nitrogen via nitrite, nitric oxide (NO, and nitrous oxide. These nitrogen oxides function as alternative electron acceptors and enable P. aeruginosa to grow under anaerobic conditions. One of the denitrification enzymes, NO reductase, is also expected to function for detoxification of NO produced by the host immune defense system. The control of the expression of these aerobic and anaerobic respiratory enzymes would contribute to the adaptation of P. aeruginosa to a wide range of environmental conditions including in the infected hosts. Characteristics of these respiratory enzymes and the regulatory system that controls the expression of the respiratory genes in the P. aeruginosa cells are overviewed in this article.

HD-GYP domain proteins regulate biofilm formation and virulence in Pseudomonas aeruginosa

DEFF Research Database (Denmark)

Ryan, Robert P.; Lucey, Jean; O'Donovan, Karen

2009-01-01

residues (YN-GYP). Here we have investigated the role of these proteins in biofilm formation, virulence factor synthesis and virulence of P. aeruginosa. Mutation of PA4108 and PA4781 led to an increase in the level of cyclic-di-GMP in P. aeruginosa, consistent with the predicted activity of the encoded......2572 had a negative influence on swarming that was cryptic and was revealed only after removal of an uncharacterized C-terminal domain. Mutation of PA4108, PA4781 and PA2572 had distinct effects on biofilm formation and architecture of P. aeruginosa. All three proteins contributed to virulence of P...

Magnesium limitation is an environmental trigger of the Pseudomonas aeruginosa biofilm lifestyle.

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Heidi Mulcahy

Full Text Available Biofilm formation is a conserved strategy for long-term bacterial survival in nature and during infections. Biofilms are multicellular aggregates of cells enmeshed in an extracellular matrix. The RetS, GacS and LadS sensors control the switch from a planktonic to a biofilm mode of growth in Pseudomonas aeruginosa. Here we detail our approach to identify environmental triggers of biofilm formation by investigating environmental conditions that repress expression of the biofilm repressor RetS. Mg(2+ limitation repressed the expression of retS leading to increased aggregation, exopolysaccharide (EPS production and biofilm formation. Repression of retS expression under Mg(2+ limitation corresponded with induced expression of the GacA-controlled small regulatory RNAs rsmZ and rsmY and the EPS biosynthesis operons pel and psl. We recently demonstrated that extracellular DNA sequesters Mg(2+ cations and activates the cation-sensing PhoPQ two-component system, which leads to increased antimicrobial peptide resistance in biofilms. Here we show that exogenous DNA and EDTA, through their ability to chelate Mg(2+, promoted biofilm formation. The repression of retS in low Mg(2+ was directly controlled by PhoPQ. PhoP also directly controlled expression of rsmZ but not rsmY suggesting that PhoPQ controls the equilibrium of the small regulatory RNAs and thus fine-tunes the expression of genes in the RetS pathway. In summary, Mg(2+ limitation is a biologically relevant environmental condition and the first bonafide environmental signal identified that results in transcriptional repression of retS and promotes P. aeruginosa biofilm formation.

Sensitivity patterns of pseudomonas aeruginosa isolates obtained from clinical specimens in peshawar

International Nuclear Information System (INIS)

Abbas, S.H.; Khan, M.Z.U.; Naeem, M.

2015-01-01

Pseudomonas aeruginosa (P. aeruginosa) is a highly virulent opportunistic pathogen and a leading cause of nosocomial infections.Affected patients are often hospitalized in an intensive care unit, and are immuno-compromised as a result of disease and treatment. Suspected P. aeruginosa require timely, adequate and empirical antibiotic therapy to ensure improved outcomes. The purpose of the study was to find the sensitivity and resistance pattern of P. aeruginosa to various groups of drugs, in clinical isolates collected from two major tertiary care hospitals of Peshawar. Methods: Different clinical isolate were taken from patients admitted in various wards of Khyber Teaching Hospital and Lady Reading Hospital Peshawar. Results: A total of 258 clinical isolates were positive for P. aeruginosa out of 2058 clinical isolates. Pseudomonas showed high degree of resistance to third generation Cephalosporins (Ceftazidime, and Ceftriaxone) and moderate degree of resistance to Quinolones and Aminoglycosides (Ofloxacin, Ciprofloxacin, Levofloxacin and Amikacin). Low resistance was observed to different combinations (Cefoperazone + Sulbactum, Piperacillin + Tazobactum). Meropenem and Imipenem had negligible resistance. Conclusion: There is growing resistance to different classes of antibiotics. Combination drugs are useful approach for empirical treatment in suspected Pseudomonas infection. Imipenem and Meropenem are extremely effective but should be in reserve. (author)

Political instability and discontinuity in Nigeria: The pre-colonial past and public goods provision under colonial and post-colonial political orders

NARCIS (Netherlands)

Papaioannou, K.I.; Dalrymple-Smith, A.E.

2015-01-01

This article explores the relative importance of pre-colonial institutional capacity and the effects of periods of peace and stability on long-term development outcomes in Nigeria. We use data on education, health, and public works at a provincial level from a variety of colonial and Nigerian state

Augmented effect of early antibiotic treatment in mice with experimental lung infections due to sequentially adapted mucoid strains of Pseudomonas aeruginosa

DEFF Research Database (Denmark)

van Gennip, M; Moser, Claus; Christensen, Louise D

2009-01-01

: A significant reduction in the number of bacteria was observed when initiating treatment 1 h post-infection compared with initiating treatment after 24 h, although the latest isolate avoided complete clearance. Early antibiotic treatment directed at the mucoid phenotype in mice also reduced the inflammation and......Background: Effects of treatment with tobramycin initiated 1 or 24 h post-infection were investigated in a new version of a pulmonary infection model in mice. The model reflects the differentiated behaviour of Pseudomonas aeruginosa mucoid strains isolated from the lungs of one chronically infected......, histopathology, and measurement of granulocyte colony-stimulating factor (G-CSF) and macrophage inflammatory protein 2 (MIP-2). Results: There was a significant reduction of bacteria when comparing treatment initiated 1 h post-infection with treatment initiated after 24 h for isolates 1997 and 2003. Treatment...

SERS detection of the biomarker hydrogen cyanide from Pseudomonas aeruginosa cultures isolated from cystic fibrosis patients

DEFF Research Database (Denmark)

Lauridsen, Rikke Kragh; Madsen Sommer, Lea Mette; Johansen, Helle Krogh

2017-01-01

Pseudomonas aeruginosa is the primary cause of chronic airway infections in cystic fibrosis (CF) patients. Persistent infections are seen from the first P. aeruginosa culture in about 75% of young CF patients, and it is important to discover new ways to detect P. aeruginosa at an earlier stage...... long-term infection, a mutation in the patho-adaptive lasR gene can alter the expression of HCN, which is why it is sometimes not possible to detect HCN in the breath of chronically infected patients. Four P. aeruginosa reference strains and 12 clinical P. aeruginosa strains isolated from CF children...... were evaluated, and HCN was clearly detected from overnight cultures of all wild type-like isolates and half of the later isolates from the same patients. The clinical impact could be that P. aeruginosa infections could be detected at an earlier stage, because daily breath sampling with an immediate...

Pseudomonas aeruginosa PAO1 exopolysaccharides are important for mixed species biofilm community development and stress tolerance

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Saravanan ePeriasamy

2015-08-01

Full Text Available Pseudomonas aeruginosa PAO1 produces three polysaccharides, alginate, Psl and Pel that play distinct roles in attachment and biofilm formation for monospecies biofilms. Considerably less is known about their role in the development of mixed species biofilm communities. This study has investigated the roles of alginate, Psl and Pel during biofilm formation of P. aeruginosa in a defined and experimentally informative mixed species biofilm community, consisting of P. aeruginosa, Pseudomonas protegens and Klebsiella pneumoniae. Loss of the Psl polysaccharide had the biggest impact on the integration of P. aeruginosa in the mixed species biofilms, where the percent composition of the psl mutant was significantly lower (0.06% than its wild-type parent (2.44%. In contrast, loss of the Pel polysaccharide had no impact on mixed species biofilm development. Loss of alginate or its overproduction resulted in P. aeruginosa representing 8.4% and 18.11%, respectively, of the mixed species biofilm. Dual species biofilms of P. aeruginosa and K. pneumoniae were not affected by loss of alginate, Pel or Psl, while the mucoid P. aeruginosa strain achieved a greater biomass than its parent strain. When P. aeruginosa was grown with P. protegens, loss of the Pel or alginate polysaccharides resulted in biofilms that were not significantly different from biofilms formed by the wild-type PAO1. In contrast, overproduction of alginate resulted in biofilms that were comprised of 35-40% of P. aeruginosa, which was significantly higher than the wild-type (5-20%. Loss of the Psl polysaccharide significantly reduced the percentage composition of P. aeruginosa in dual species biofilms with P. protegens (<1%. Loss of the Psl polysaccharide significantly disrupted the communal stress resistance of the three species biofilms. Thus, the polysaccharide composition of an individual species significantly impacts mixed species biofilm development and the emergent properties of such

Cell death in Pseudomonas aeruginosa biofilm development

DEFF Research Database (Denmark)

Webb, J.S.; Thompson, L.S.; James, S.

2003-01-01

Bacteria growing in biofilms often develop multicellular, three-dimensional structures known as microcolonies. Complex differentiation within biofilms of Pseudomonas aeruginosa occurs, leading to the creation of voids inside microcolonies and to the dispersal of cells from within these voids....... However, key developmental processes regulating these events are poorly understood. A normal component of multicellular development is cell death. Here we report that a repeatable pattern of cell death and lysis occurs in biofilms of P. aeruginosa during the normal course of development. Cell death...... occurred with temporal and spatial organization within biofilms, inside microcolonies, when the biofilms were allowed to develop in continuous-culture flow cells. A subpopulation of viable cells was always observed in these regions. During the onset of biofilm killing and during biofilm development...

Comparison of high-resolution computed tomography findings between Pseudomonas aeruginosa pneumonia and Cytomegalovirus pneumonia

International Nuclear Information System (INIS)

Omeri, Ahmad Khalid; Okada, Fumito; Takata, Shoko; Ono, Asami; Sato, Haruka; Mori, Hiromu; Nakayama, Tomoko; Ando, Yumiko; Hiramatsu, Kazufumi

2014-01-01

To compare pulmonary high-resolution CT (HRCT) findings in patients with Pseudomonas aeruginosa pneumonia to HRCT findings in patients with Cytomegalovirus (CMV) pneumonia. We studied 124 patients (77 men, 47 women; age range, 20-89 years; mean age, 65.4 years) with P. aeruginosa pneumonia and 44 patients (22 men, 22 women; age range, 36-86 years; mean age, 63.2 years) with CMV pneumonia. CT findings of consolidation (p < 0.005), bronchial wall thickening (p < 0.001), cavity (p < 0.05), and pleural effusion (p < 0.001) were significantly more frequent in patients with P. aeruginosa pneumonia than in those with CMV pneumonia. Centrilobular nodules, a crazy-paving appearance, and nodules were significantly more frequent in patients with CMV pneumonia than in those with P. aeruginosa pneumonia (all p < 0.001). Pulmonary HRCT findings, such as bronchial wall thickening, crazy-paving appearance, and nodules may be useful in distinguishing between P. aeruginosa pneumonia and CMV pneumonia. (orig.)

Comparison of high-resolution computed tomography findings between Pseudomonas aeruginosa pneumonia and Cytomegalovirus pneumonia

Energy Technology Data Exchange (ETDEWEB)

Omeri, Ahmad Khalid; Okada, Fumito; Takata, Shoko; Ono, Asami; Sato, Haruka; Mori, Hiromu [Oita University Faculty of Medicine, Department of Radiology, Yufu, Oita (Japan); Nakayama, Tomoko [Oita Red Cross Hospital, Department of Radiology, Oita (Japan); Ando, Yumiko [Oita Nishibeppu National Hospital, Department of Radiology, Oita (Japan); Hiramatsu, Kazufumi [Oita University Hospital, Hospital Infection Control Center, Oita (Japan)

2014-12-15

To compare pulmonary high-resolution CT (HRCT) findings in patients with Pseudomonas aeruginosa pneumonia to HRCT findings in patients with Cytomegalovirus (CMV) pneumonia. We studied 124 patients (77 men, 47 women; age range, 20-89 years; mean age, 65.4 years) with P. aeruginosa pneumonia and 44 patients (22 men, 22 women; age range, 36-86 years; mean age, 63.2 years) with CMV pneumonia. CT findings of consolidation (p < 0.005), bronchial wall thickening (p < 0.001), cavity (p < 0.05), and pleural effusion (p < 0.001) were significantly more frequent in patients with P. aeruginosa pneumonia than in those with CMV pneumonia. Centrilobular nodules, a crazy-paving appearance, and nodules were significantly more frequent in patients with CMV pneumonia than in those with P. aeruginosa pneumonia (all p < 0.001). Pulmonary HRCT findings, such as bronchial wall thickening, crazy-paving appearance, and nodules may be useful in distinguishing between P. aeruginosa pneumonia and CMV pneumonia. (orig.)

Hospital costs of nosocomial multi-drug resistant Pseudomonas aeruginosa acquisition.

Science.gov (United States)

Morales, Eva; Cots, Francesc; Sala, Maria; Comas, Mercè; Belvis, Francesc; Riu, Marta; Salvadó, Margarita; Grau, Santiago; Horcajada, Juan P; Montero, Maria Milagro; Castells, Xavier

2012-05-23

We aimed to assess the hospital economic costs of nosocomial multi-drug resistant Pseudomonas aeruginosa acquisition. A retrospective study of all hospital admissions between January 1, 2005, and December 31, 2006 was carried out in a 420-bed, urban, tertiary-care teaching hospital in Barcelona (Spain). All patients with a first positive clinical culture for P. aeruginosa more than 48 h after admission were included. Patient and hospitalization characteristics were collected from hospital and microbiology laboratory computerized records. According to antibiotic susceptibility, isolates were classified as non-resistant, resistant and multi-drug resistant. Cost estimation was based on a full-costing cost accounting system and on the criteria of clinical Activity-Based Costing methods. Multivariate analyses were performed using generalized linear models of log-transformed costs. Cost estimations were available for 402 nosocomial incident P. aeruginosa positive cultures. Their distribution by antibiotic susceptibility pattern was 37.1% non-resistant, 29.6% resistant and 33.3% multi-drug resistant. The total mean economic cost per admission of patients with multi-drug resistant P. aeruginosa strains was higher than that for non-resistant strains (15,265 vs. 4,933 Euros). In multivariate analysis, resistant and multi-drug resistant strains were independently predictive of an increased hospital total cost in compared with non-resistant strains (the incremental increase in total hospital cost was more than 1.37-fold and 1.77-fold that for non-resistant strains, respectively). P. aeruginosa multi-drug resistance independently predicted higher hospital costs with a more than 70% increase per admission compared with non-resistant strains. Prevention of the nosocomial emergence and spread of antimicrobial resistant microorganisms is essential to limit the strong economic impact.

Diversity of Antimicrobial Resistance and Virulence Determinants in Pseudomonas aeruginosa Associated with Fresh Vegetables

OpenAIRE

Allydice-Francis, Kashina; Brown, Paul D.

2012-01-01

With the increased focus on healthy eating and consuming raw vegetables, this study assessed the extent of contamination of fresh vegetables by Pseudomonas aeruginosa in Jamaica and examined the antibiotic susceptibility profiles and the presence of various virulence associated determinants of P. aeruginosa. Analyses indicated that vegetables from retail markets and supermarkets were widely contaminated by P. aeruginosa; produce from markets were more frequently contaminated, but the differen...

Electrochemical sensors for identifying pyocyanin production in clinical Pseudomonas aeruginosa isolates.

Science.gov (United States)

Sismaet, Hunter J; Pinto, Ameet J; Goluch, Edgar D

2017-11-15

In clinical practice, delays in obtaining culture results impact patient care and the ability to tailor antibiotic therapy. Despite the advancement of rapid molecular diagnostics, the use of plate cultures inoculated from swab samples continues to be the standard practice in clinical care. Because the inoculation culture process can take between 24 and 48h before a positive identification test can be run, there is an unmet need to develop rapid throughput methods for bacterial identification. Previous work has shown that pyocyanin can be used as a rapid, redox-active biomarker for identifying Pseudomonas aeruginosa in clinical infections. However, further validation is needed to confirm pyocyanin production occurs in all clinical strains of P. aeruginosa. Here, we validate this electrochemical detection strategy using clinical isolates obtained from patients with hospital-acquired infections or with cystic fibrosis. Square-wave voltammetric scans of 94 different clinical P. aeruginosa isolates were taken to measure the concentration of pyocyanin. The results showed that all isolates produced measureable concentrations of pyocyanin with production rates correlated with patient symptoms and comorbidity. Further bioinformatics analysis confirmed that 1649 genetically sequenced strains (99.9%) of P. aeruginosa possess the two genes (PhzM and PhzS) necessary to produce pyocyanin, supporting the specificity of this biomarker. Confirming the production of pyocyanin by all clinically-relevant strains of P. aeruginosa is a significant step towards validating this strategy for rapid, point-of-care diagnostics. Copyright © 2017 Elsevier B.V. All rights reserved.

An outbreak of hospital-acquired Pseudomonas aeruginosa infection caused by contaminated bottled water in intensive care units.

Science.gov (United States)

Eckmanns, T; Oppert, M; Martin, M; Amorosa, R; Zuschneid, I; Frei, U; Rüden, H; Weist, K

2008-05-01

This study describes an outbreak of Pseudomonas aeruginosa infections caused by contaminated bottled still water (BSW) in six intensive care units (ICUs) of a German university hospital. Clinical and environmental samples from these units were cultured and genotyped by amplified fragment-length polymorphism and pulsed-field gel electrophoresis analysis. Microbiological results were reviewed on a weekly basis to determine the number of P. aeruginosa infections and colonisations of ICU patients. Clinical specimens from 19 ICU patients--15 infections and four colonisations--yielded the same strain of P. aeruginosa. Furthermore, four of 103 environmental samples also yielded P. aeruginosa. However, only a P. aeruginosa strain isolated from unopened BSW was genetically identical to the P. aeruginosa strain isolated from the patients. In the 42-week period before the outbreak, the mean weekly number of new ICU patients infected or colonised with P. aeruginosa was 46.9 (95% CI 40.7-53.1)/1000 bed-days. During the 6-week period of the outbreak, the weekly number of new patients with P. aeruginosa was 88.9 (95% CI 54.3-122.2)/1000 bed-days. This number returned to the previous level after removal of the BSW. Thus, the microbiological and epidemiological findings revealed that the outbreak was related to BSW contaminated with P. aeruginosa. It was concluded that all untested BSW should be removed from ICUs.

Pyoverdine, the Major Siderophore in Pseudomonas aeruginosa, Evades NGAL Recognition

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Mary E. Peek

2012-01-01

Full Text Available Pseudomonas aeruginosa is the most common pathogen that persists in the cystic fibrosis lungs. Bacteria such as P. aeruginosa secrete siderophores (iron-chelating molecules and the host limits bacterial growth by producing neutrophil-gelatinase-associated lipocalin (NGAL that specifically scavenges bacterial siderophores, therefore preventing bacteria from establishing infection. P. aeruginosa produces a major siderophore known as pyoverdine, found to be important for bacterial virulence and biofilm development. We report that pyoverdine did not bind to NGAL, as measured by tryptophan fluorescence quenching, while enterobactin bound to NGAL effectively causing a strong response. The experimental data indicate that pyoverdine evades NGAL recognition. We then employed a molecular modeling approach to simulate the binding of pyoverdine to human NGAL using NGAL’s published crystal structures. The docking of pyoverdine to NGAL predicted nine different docking positions; however, neither apo- nor ferric forms of pyoverdine docked into the ligand-binding site in the calyx of NGAL where siderophores are known to bind. The molecular modeling results offer structural support that pyoverdine does not bind to NGAL, confirming the results obtained in the tryptophan quenching assay. The data suggest that pyoverdine is a stealth siderophore that evades NGAL recognition allowing P. aeruginosa to establish chronic infections in CF lungs.

Ocorrência de linhagens de Pseudomonas aeruginosa cloro resistentes em águas de diferentes origens = Ocurrence of chlorine resistant strains of Pseudomonas aeruginosa from different water sources

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Glícia Maria Torres Calazans

2007-07-01

Full Text Available Pseudomonas aeruginosa é conhecida por sua versatilidade metabólica e extrema capacidade de adaptação a diferentes ambientes, inclusive aquáticos. Para desinfecção de águas, o cloro e agentes que contêm cloro continuam sendo os mais usados no mundo. O objetivo deste trabalho foi avaliar a resistência ao cloro de linhagens de P. aeruginosa, isoladas de amostras de águas de diversos ambientes. Foram testados diferentes tempos de contato (1, 5, 10, 20, 30 e 40 minutos e soluções aquosas de cloro, com concentrações definidascom base na legislação vigente no país para água potável: 0,5; 1,0 e 2,0 ppm. O teste de resistência ao cloro foi desenvolvido por meio da exposição direta das bactérias às soluções. Os resultados revelaram que P. aeruginosa, isoladas de diferentes fontes de água, têm ahabilidade de sobreviver a diferentes concentrações de cloro. Na concentração de 1 ppm, a maioria das linhagens não foi inibida. As linhagens mais resistentes ao cloro também apresentaram relação de multirresistência à maioria dos antibióticos testados.The nutritional versatility and the adaptability of Pseudomonas aeruginosa to different environments, including water, are well known. Chlorine and other chlorine agents are used as water disinfecting all around the world. The aim of this work was to evaluate the possible chlorine resistance amongst P. aeruginosa strains isolated from different aquatic sources by using different contact time (1, 5, 10, 20, 30 and 40 minutes in solutions with known chlorine concentrations according current legislation in the country to potable water: 0.5; 1.0 and 2.0 ppm. The chlorine resistance test was done by direct exposure of P. aeruginosa under a solution with known chlorine concentration. Results showed that P. aeruginosa strains isolated from different aquatic sources are able tosurvive in different chlorine concentrations. At 1 ppm, most of them were not inhibited. It was also observed

RsmV a small non-coding regulatory RNA in Pseudomonas aeruginosa that sequesters RsmA and RsmF from target mRNAs.

Science.gov (United States)

Janssen, Kayley H; Diaz, Manisha R; Gode, Cindy J; Wolfgang, Matthew C; Yahr, Timothy L

2018-06-04

The Gram-negative opportunistic pathogen Pseudomonas aeruginosa has distinct genetic programs that favor either acute or chronic virulence gene expression. Acute virulence is associated with twitching and swimming motility, expression of a type III secretion system (T3SS), and the absence of alginate, Psl, or Pel polysaccharide production. Traits associated with chronic infection include growth as a biofilm, reduced motility, and expression of a type VI secretion system (T6SS). The Rsm post-transcriptional regulatory system plays important roles in the inverse control of phenotypes associated with acute and chronic virulence. RsmA and RsmF are RNA-binding proteins that interact with target mRNAs to control gene expression at the post-transcriptional level. Previous work found that RsmA activity is controlled by at least three small, non-coding regulatory RNAs (RsmW, RsmY, and RsmZ). In this study, we took an in-silico approach to identify additional sRNAs that might function in the sequestration of RsmA and/or RsmF and identified RsmV, a 192 nt transcript with four predicted RsmA/RsmF consensus binding sites. RsmV is capable of sequestering RsmA and RsmF in vivo to activate translation of tssA1 , a component of the T6SS, and to inhibit T3SS gene expression. Each of the predicted RsmA/RsmF consensus binding sites contribute to RsmV activity. Electrophoretic mobility shifts assays show that RsmF binds RsmV with >10-fold higher affinity than RsmY and RsmZ. Gene expression studies revealed that the temporal expression pattern of RsmV differs from RsmW, RsmY, and RsmZ. These findings suggest that each sRNA may play distinct roles in controlling RsmA and RsmF activity. IMPORTANCE The CsrA/RsmA family of RNA-binding proteins play important roles in post-transcriptional control of gene expression. The activity of CsrA/RsmA proteins is controlled by small non-coding RNAs that function as decoys to sequester CsrA/RsmA from target mRNAs. Pseudomonas aeruginosa has two Csr

Roosting Colony of Cormorants (Phalacrocorax Carbo Sinensis L. as a Source of Nutrients for the Lake

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Piotr Klimaszyk

2015-03-01

Full Text Available Since 2005, great cormorants have been observed on the Lake Góreckie (Wielkopolski National Park shoreline. The population of these birds occurring within the lake has gradually increased. In autumn 2008, more than 100 individuals were observed. In the period 2009-2012 the number of birds occupying the island periodically exceeded 250 individuals. So far, there is no breeding colony of great cormorants, but the birds have established a roosting colony on the island. In the period 2009-2012 we conducted research on the impact of the colony of great cormorants on the accumulation of nitrogen, phosphorus and other elements in soils beneath the colony and transfer of chemical elements from the colony to a nearby freshwater ecosystem. Our results show that a relatively small and recent colony of great cormorants can significantly affect the chemistry of soil. Compared to a control, the soil beneath the colony was characterized by statistically higher concentrations of nitrogen and phosphorus. A significant accumulation of nutrients was observed in the topsoil zone (to a depth of about 20 cm. Enrichment of soil in chemical elements has resulted in their further transport to a nearby lake. Compared to the control, the groundwater and surface runoff from the colony area revealed several-fold higher concentrations of nitrogen and phosphorus. The maximum abundance of cormorants in the roosting colony was reflected in the elevated concentrations of nitrogen and phosphorus in the littoral water near the colony. Our study demonstrates that the roosting colony of great cormorants can play a significant role in accelerating the eutrophication of surface waters.

A diagnostic PCR assay for the detection of an Australian epidemic strain of Pseudomonas aeruginosa

Science.gov (United States)

2010-01-01

Background Chronic lung infection with the bacterium Pseudomonas aeruginosa is one of the hallmarks of cystic fibrosis (CF) and is associated with worsening lung function, increased hospitalisation and reduced life expectancy. A virulent clonal strain of P. aeruginosa (Australian epidemic strain I; AES-I) has been found to be widespread in CF patients in eastern Australia. Methods Suppression subtractive hybridization (SSH) was employed to identify genetic sequences that are present in the AES-I strain but absent from the sequenced reference strain PAO1. We used PCR to evaluate the distribution of several of the AES-I loci amongst a collection of 188 P. aeruginosa isolates which was comprised of 35 AES-I isolates (as determined by PFGE), 78 non-AES-I CF isolates including other epidemic CF strains as well as 69 P. aeruginosa isolates from other clinical and environmental sources. Results We have identified a unique AES-I genetic locus that is present in all 35 AES-I isolates tested and not present in any of the other 153 P. aeruginosa strains examined. We have used this unique AES-I locus to develop a diagnostic PCR and a real-time PCR assay to detect the presence of P. aeruginosa and AES-I in patient sputum samples. Conclusions We have developed diagnostic PCR assays that are 100% sensitive and 100% specific for the P. aeruginosa strain AES-I. We have also shown that Whatman FTA® Elute cards may be used with PCR-based assays to rapidly detect the presence of P. aeruginosa strains in CF sputum. PMID:20637114

A diagnostic PCR assay for the detection of an Australian epidemic strain of Pseudomonas aeruginosa

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Murphy Anna

2010-07-01

Full Text Available Abstract Background Chronic lung infection with the bacterium Pseudomonas aeruginosa is one of the hallmarks of cystic fibrosis (CF and is associated with worsening lung function, increased hospitalisation and reduced life expectancy. A virulent clonal strain of P. aeruginosa (Australian epidemic strain I; AES-I has been found to be widespread in CF patients in eastern Australia. Methods Suppression subtractive hybridization (SSH was employed to identify genetic sequences that are present in the AES-I strain but absent from the sequenced reference strain PAO1. We used PCR to evaluate the distribution of several of the AES-I loci amongst a collection of 188 P. aeruginosa isolates which was comprised of 35 AES-I isolates (as determined by PFGE, 78 non-AES-I CF isolates including other epidemic CF strains as well as 69 P. aeruginosa isolates from other clinical and environmental sources. Results We have identified a unique AES-I genetic locus that is present in all 35 AES-I isolates tested and not present in any of the other 153 P. aeruginosa strains examined. We have used this unique AES-I locus to develop a diagnostic PCR and a real-time PCR assay to detect the presence of P. aeruginosa and AES-I in patient sputum samples. Conclusions We have developed diagnostic PCR assays that are 100% sensitive and 100% specific for the P. aeruginosa strain AES-I. We have also shown that Whatman FTA® Elute cards may be used with PCR-based assays to rapidly detect the presence of P. aeruginosa strains in CF sputum.

Pseudomonas aeruginosa ventilator-associated pneumonia management

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Ramírez-Estrada, Sergio; Borgatta, Bárbara; Rello, Jordi

2016-01-01

Ventilator-associated pneumonia is the most common infection in intensive care unit patients associated with high morbidity rates and elevated economic costs; Pseudomonas aeruginosa is one of the most frequent bacteria linked with this entity, with a high attributable mortality despite adequate treatment that is increased in the presence of multiresistant strains, a situation that is becoming more common in intensive care units. In this manuscript, we review the current management of ventilator-associated pneumonia due to P. aeruginosa, the most recent antipseudomonal agents, and new adjunctive therapies that are shifting the way we treat these infections. We support early initiation of broad-spectrum antipseudomonal antibiotics in present, followed by culture-guided monotherapy de-escalation when susceptibilities are available. Future management should be directed at blocking virulence; the role of alternative strategies such as new antibiotics, nebulized treatments, and vaccines is promising. PMID:26855594

Plant-expressed pyocins for control of Pseudomonas aeruginosa.

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Šarūnas Paškevičius

Full Text Available The emergence, persistence and spread of antibiotic-resistant human pathogenic bacteria heralds a growing global health crisis. Drug-resistant strains of gram-negative bacteria, such as Pseudomonas aeruginosa, are especially dangerous and the medical and economic burden they impose underscore the critical need for finding new antimicrobials. Recent studies have demonstrated that plant-expressed bacteriocins of the colicins family can be efficient antibacterials against all major enteropathogenic strains of E. coli. We extended our studies of colicin-like bacteriocins to pyocins, which are produced by strains of P. aeruginosa for ecological advantage against other strains of the same species. Using a plant-based transient expression system, we expressed six different pyocins, namely S5, PaeM, L1, L2, L3 and one new pyocin, PaeM4, and purified them to homogeneity. Among these pyocins, PaeM4 demonstrated the broadest spectrum of activity by controlling 53 of 100 tested clinical isolates of P. aeruginosa. The activity of plant-made pyocins was confirmed in the agar drop, liquid culture susceptibility and biofilm assays, and in the Galleria mellonella animal infection model.

In-vivo expression profiling of Pseudomonas aeruginosa infections reveals niche-specific and strain-independent transcriptional programs.

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Piotr Bielecki

Full Text Available Pseudomonas aeruginosa is a threatening, opportunistic pathogen causing disease in immunocompromised individuals. The hallmark of P. aeruginosa virulence is its multi-factorial and combinatorial nature. It renders such bacteria infectious for many organisms and it is often resistant to antibiotics. To gain insights into the physiology of P. aeruginosa during infection, we assessed the transcriptional programs of three different P. aeruginosa strains directly after isolation from burn wounds of humans. We compared the programs to those of the same strains using two infection models: a plant model, which consisted of the infection of the midrib of lettuce leaves, and a murine tumor model, which was obtained by infection of mice with an induced tumor in the abdomen. All control conditions of P. aeruginosa cells growing in suspension and as a biofilm were added to the analysis. We found that these different P. aeruginosa strains express a pool of distinct genetic traits that are activated under particular infection conditions regardless of their genetic variability. The knowledge herein generated will advance our understanding of P. aeruginosa virulence and provide valuable cues for the definition of prospective targets to develop novel intervention strategies.

Queen promiscuity lowers disease within honeybee colonies

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Seeley, Thomas D; Tarpy, David R

2006-01-01

Most species of social insects have singly mated queens, but in some species each queen mates with numerous males to create a colony with a genetically diverse worker force. The adaptive significance of polyandry by social insect queens remains an evolutionary puzzle. Using the honeybee (Apis mellifera), we tested the hypothesis that polyandry improves a colony's resistance to disease. We established colonies headed by queens that had been artificially inseminated by either one or 10 drones. Later, we inoculated these colonies with spores of Paenibacillus larvae, the bacterium that causes a highly virulent disease of honeybee larvae (American foulbrood). We found that, on average, colonies headed by multiple-drone inseminated queens had markedly lower disease intensity and higher colony strength at the end of the summer relative to colonies headed by single-drone inseminated queens. These findings support the hypothesis that polyandry by social insect queens is an adaptation to counter disease within their colonies. PMID:17015336

Respiratory syncytial virus infection enhances Pseudomonas aeruginosa biofilm growth through dysregulation of nutritional immunity.

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Hendricks, Matthew R; Lashua, Lauren P; Fischer, Douglas K; Flitter, Becca A; Eichinger, Katherine M; Durbin, Joan E; Sarkar, Saumendra N; Coyne, Carolyn B; Empey, Kerry M; Bomberger, Jennifer M

2016-02-09

Clinical observations link respiratory virus infection and Pseudomonas aeruginosa colonization in chronic lung disease, including cystic fibrosis (CF) and chronic obstructive pulmonary disease. The development of P. aeruginosa into highly antibiotic-resistant biofilm communities promotes airway colonization and accounts for disease progression in patients. Although clinical studies show a strong correlation between CF patients' acquisition of chronic P. aeruginosa infections and respiratory virus infection, little is known about the mechanism by which chronic P. aeruginosa infections are initiated in the host. Using a coculture model to study the formation of bacterial biofilm formation associated with the airway epithelium, we show that respiratory viral infections and the induction of antiviral interferons promote robust secondary P. aeruginosa biofilm formation. We report that the induction of antiviral IFN signaling in response to respiratory syncytial virus (RSV) infection induces bacterial biofilm formation through a mechanism of dysregulated iron homeostasis of the airway epithelium. Moreover, increased apical release of the host iron-binding protein transferrin during RSV infection promotes P. aeruginosa biofilm development in vitro and in vivo. Thus, nutritional immunity pathways that are disrupted during respiratory viral infection create an environment that favors secondary bacterial infection and may provide previously unidentified targets to combat bacterial biofilm formation.

In vitro susceptibility of aural isolates of Pseudomonas aeruginosa to commonly used ototopical antibiotics.

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Dohar, J E; Kenna, M A; Wadowsky, R M

1996-03-01

The choice of antimicrobial agents used to treat Pseudomonas aeruginosa infections of the ear is quite empiric. Yet in spite of this, very little has been published examining susceptibility patterns of aural isolates of P. aeruginosa. Recently, increasing concern has emerged over the development of resistance to many of the commonly used ototopical preparations with activity against P. aeruginosa. This concern stems from the fact that these preparations have been in use for a long time, and P. aeruginosa is known to develop resistance fairly readily. We prospectively studied the susceptibilities of aural isolates of P. aeruginosa in 231 consecutive children who were seen in the outpatient Pediatric Otolaryngology Department at Children's Hospital of Pittsburgh during the years 1992 and 1993. The agents tested included neomycin, polymyxin B, colistin, and norfloxacin. We found that only 17.8% of the isolates were sensitive to neomycin, as opposed to > 95% for each of the other agents tested (polymyxin B, 99.6%; colistin, 97.4%; and norfloxacin, 98.3%). This difference proved to be statistically significant (p < 0.05). Given the concern of aminoglycoside-induced ototoxicity and the high rate of neomycin resistance, we believe that further investigation of other alternative ototopic agents with activity against P. aeruginosa is warranted.

Bioleaching of copper oxide ore by Pseudomonas aeruginosa

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Shabani, M. A.; Irannajad, M.; Azadmehr, A. R.; Meshkini, M.

2013-12-01

Bioleaching is an environmentally friendly method for extraction of metal from ores. In this study, bioleaching of copper oxide ore by Pseudomonas aeruginosa was investigated. Pseudomonas aeruginosa is a heterotrophic bacterium that can produce various organic acids in an appropriate culture medium, and these acids can operate as leaching agents. The parameters, such as particle size, glucose percentage in the culture medium, bioleaching time, and solid/liquid ratio were optimized. Optimum bioleaching conditions were found as follows: particle size of 150-177 μm, glucose percentage of 6%, bioleaching time of 8 d, and solid/liquid ratio of 1:80. Under these conditions, 53% of copper was extracted.

Pseudomonas aeruginosa Bacteremia among Immunocompetent and Immunocompromised Patients: Relation to Initial Antibiotic Therapy and Survival.

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Migiyama, Yohei; Yanagihara, Katsunori; Kaku, Norihito; Harada, Yosuke; Yamada, Koichi; Nagaoka, Kentaro; Morinaga, Yoshitomo; Akamatsu, Norihiko; Matsuda, Junichi; Izumikawa, Koichi; Kohrogi, Hirotsugu; Kohno, Shigeru

2016-01-01

Pseudomonas aeruginosa bacteremia occurs mainly in immunocompromised patients. However, P. aeruginosa bacteremia in immunocompetent patients has also been reported. The aim of this study was to evaluate the clinical characteristics of P. aeruginosa bacteremia in relation to the immune status of the patients. The medical records of 126 adult patients with P. aeruginosa bacteremia in Nagasaki University Hospital were retrospectively reviewed between January 2003 and December 2012. Of 126 patients with P. aeruginosa bacteremia, 60 patients (47.6%) were classified as immunocompetent. Mortality in immunocompetent patients tended to be lower than in immunocompromised patients (7-day mortality, 8% vs. 30%, P antibiotic therapy (HR: 0.21, P immunocompromised, but not immunocompetent patients, initial appropriate antibiotic therapy was associated with lower mortality (30-day mortality 20.5% vs. 66.7%, P < 0.01 by log-rank test).

Relationship between cystic fibrosis respiratory tract bacterial communities and age, genotype, antibiotics and Pseudomonas aeruginosa.

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Klepac-Ceraj, Vanja; Lemon, Katherine P; Martin, Thomas R; Allgaier, Martin; Kembel, Steven W; Knapp, Alixandra A; Lory, Stephen; Brodie, Eoin L; Lynch, Susan V; Bohannan, Brendan J M; Green, Jessica L; Maurer, Brian A; Kolter, Roberto

2010-05-01

Polymicrobial bronchopulmonary infections in cystic fibrosis (CF) cause progressive lung damage and death. Although the arrival of Pseudomonas aeruginosa often heralds a more rapid rate of pulmonary decline, there is significant inter-individual variation in the rate of decline, the causes of which remain poorly understood. By coupling culture-independent methods with ecological analyses, we discovered correlations between bacterial community profiles and clinical disease markers in respiratory tracts of 45 children with CF. Bacterial community complexity was inversely correlated with patient age, presence of P. aeruginosa and antibiotic exposure, and was related to CF genotype. Strikingly, bacterial communities lacking P. aeruginosa were much more similar to each other than were those containing P. aeruginosa, regardless of antibiotic exposure. This suggests that community composition might be a better predictor of disease progression than the presence of P. aeruginosa alone and deserves further study.

Chemical Inhibition of Kynureninase Reduces Pseudomonas aeruginosa Quorum Sensing and Virulence Factor Expression.

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Kasper, Stephen H; Bonocora, Richard P; Wade, Joseph T; Musah, Rabi Ann; Cady, Nathaniel C

2016-04-15

The opportunistic pathogen Pseudomonas aeruginosa utilizes multiple quorum sensing (QS) pathways to coordinate an arsenal of virulence factors. We previously identified several cysteine-based compounds inspired by natural products from the plant Petiveria alliacea which are capable of antagonizing multiple QS circuits as well as reducing P. aeruginosa biofilm formation. To understand the global effects of such compounds on virulence factor production and elucidate their mechanism of action, RNA-seq transcriptomic analysis was performed on P. aeruginosa PAO1 exposed to S-phenyl-l-cysteine sulfoxide, the most potent inhibitor from the prior study. Exposure to this inhibitor down-regulated expression of several QS-regulated virulence operons (e.g., phenazine biosynthesis, type VI secretion systems). Interestingly, many genes that were differentially regulated pertain to the related metabolic pathways that yield precursors of pyochelin, tricarboxylic acid cycle intermediates, phenazines, and Pseudomonas quinolone signal (PQS). Activation of the MexT-regulon was also indicated, including the multidrug efflux pump encoded by mexEF-oprN, which has previously been shown to inhibit QS and pathogenicity. Deeper investigation of the metabolites involved in these systems revealed that S-phenyl-l-cysteine sulfoxide has structural similarity to kynurenine, a precursor of anthranilate, which is critical for P. aeruginosa virulence. By supplementing exogenous anthranilate, the QS-inhibitory effect was reversed. Finally, it was shown that S-phenyl-l-cysteine sulfoxide competitively inhibits P. aeruginosa kynureninase (KynU) activity in vitro and reduces PQS production in vivo. The kynurenine pathway has been implicated in P. aeruginosa QS and virulence factor expression; however, this is the first study to show that targeted inhibition of KynU affects P. aeruginosa gene expression and QS, suggesting a potential antivirulence strategy.

Synergistic Efficacy of Aedes aegypti Antimicrobial Peptide Cecropin A2 and Tetracycline against Pseudomonas aeruginosa

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Zheng, Zhaojun; Tharmalingam, Nagendran; Liu, Qingzhong; Kim, Wooseong; Fuchs, Beth Burgwyn; Zhang, Rijun; Vilcinskas, Andreas

2017-01-01

ABSTRACT The increasing prevalence of antibiotic resistance has created an urgent need for alternative drugs with new mechanisms of action. Antimicrobial peptides (AMPs) are promising candidates that could address the spread of multidrug-resistant bacteria, either alone or in combination with conventional antibiotics. We studied the antimicrobial efficacy and bactericidal mechanism of cecropin A2, a 36-residue α-helical cationic peptide derived from Aedes aegypti cecropin A, focusing on the common pathogen Pseudomonas aeruginosa. The peptide showed little hemolytic activity and toxicity toward mammalian cells, and the MICs against most clinical P. aeruginosa isolates were 32 to 64 μg/ml, and its MICs versus other Gram-negative bacteria were 2 to 32 μg/ml. Importantly, cecropin A2 demonstrated synergistic activity against P. aeruginosa when combined with tetracycline, reducing the MICs of both agents by 8-fold. The combination was also effective in vivo in the P. aeruginosa/Galleria mellonella model (P < 0.001). We found that cecropin A2 bound to P. aeruginosa lipopolysaccharides, permeabilized the membrane, and interacted with the bacterial genomic DNA, thus facilitating the translocation of tetracycline into the cytoplasm. In summary, the combination of cecropin A2 and tetracycline demonstrated synergistic antibacterial activity against P. aeruginosa in vitro and in vivo, offering an alternative approach for the treatment of P. aeruginosa infections. PMID:28483966

Royal Jelly Inhibits Pseudomonas aeruginosa Adherence and Reduces Excessive Inflammatory Responses in Human Epithelial Cells

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Heni Susilowati

2017-01-01

Full Text Available Pseudomonas aeruginosa is a Gram-negative bacterium and causes respiratory infection especially in elderly patients. Royal jelly has been used worldwide as a traditional remedy and as a nutrient; however, the effect against P. aeruginosa is unclear. The aim of this study was to analyze antibacterial, antiadherent, and anti-inflammatory effects of royal jelly against P. aeruginosa. Wild-type strain PAO1 and clinical isolates of P. aeruginosa were used for antibacterial assay and antiadherent assay to abiotic surface and epithelial cells, which are pharynx (Detroit 562 and lung (NCI-H292 epithelial cells. In anti-inflammatory assay, epithelial cells were pretreated with royal jelly before bacterial exposure to investigate its inhibitory effect on interleukin (IL-8 and macrophage inflammatory protein-3α/CCL20 overproduction. Although royal jelly did not have antibacterial activity at concentration of 50% w/v, antiadherent activity was confirmed on the abiotic surface and epithelial cells under concentration of 25%. Pretreatment with royal jelly significantly inhibited overproduction of IL-8 and CCL20 from both cells. These results demonstrated that royal jelly inhibits P. aeruginosa adherence and protects epithelial cells from excessive inflammatory responses against P. aeruginosa infection. Our findings suggested that royal jelly may be a useful supplement as complementary and alternative medicine for preventing respiratory infection caused by P. aeruginosa.

A case of orbital apex syndrome due to Pseudomonas aeruginosa infection

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Takeshi Kusunoki

2011-11-01

Full Text Available Orbital apex syndrome is commonly been thought to have a poor prognosis. Many cases of this syndrome have been reported to be caused by paranasal sinus mycosis. We encountered a very rare case (60-year-old woman of sinusitis with orbital apex syndrome due to Pseudomonas aeruginosa infection. She had received insulin and dialysis for diabtes and diabetic nephropathy, moreover anticoagulants after heart by-pass surgery. She underwent endoscopic sinus operation and was treated with antibiotics, but her loss of left vision did not improve. Recently, sinusitis cases due to Pseudomonas aeruginosa were reported to be a increasing. Therefore, we should consider the possibility of Pseudomonas aeruginosa as well as mycosis as infections of the sinus, especially inpatients who are immunocompromised body.

Pseudomoniasis phytotherapy: A review on most important Iranian medicinal plants effective on Pseudomonas aeruginosa

OpenAIRE

Mahmoud Bahmani; Mahmoud Rafieian-Kopaei; Hassan Hassanzadazar; Morovat Taherikalani

2016-01-01

Background and Objectives: Pseudomonas aeruginosa is a Gram-negative, aerobic bacterium found in water and soil. It is a normal flora in skin and gastrointestinal tract of human beings. P. aeruginosa as an opportunistic pathogen involved in nosocomial infections having multiple pathogenic factors and shows high rate of resistance to different antibiotics. The aim of this study was to identify the most important native medicinal plants of Iran effective on P. aeruginosa.Materials and Methods: ...

Pseudomonas aeruginosa in Swimming Pool Water: Evidences and Perspectives for a New Control Strategy

OpenAIRE

Guida, Marco; Di Onofrio, Valeria; Gall?, Francesca; Gesuele, Renato; Valeriani, Federica; Liguori, Renato; Romano Spica, Vincenzo; Liguori, Giorgio

2016-01-01

Pseudomonas aeruginosa is frequently isolated in swimming pool settings. Nine recreational and rehabilitative swimming pools were monitored according to the local legislation. The presence of P. aeruginosa was correlated to chlorine concentration. The ability of the isolates to form a biofilm on plastic materials was also investigated. In 59.5% of the samples, microbial contamination exceeded the threshold values. P. aeruginosa was isolated in 50.8% of these samples. The presence of P. aerugi...

[Effect of habitat and interspecific competition on Apis cerana cerana colony distribution].

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Yu, Linsheng; Han, Shengming

2003-04-01

Habitat change and interspecific competition were the main factors affecting, Apis cerana cerana colony distribution among Wannan and Wanxi Dabie mountainous areas, Jianghuai area and Huaibei plain. Wannan and Wanxi Dabie mountainous areas were the ideal places for Apis cerana cerana' habitation and propogation, in which, there were integrated natural vegetation, fine ecological condition, abundant nectariferous plants, and Apis cerana cerana had large colony size, wide distribution, high density, no disturbances of natural mating, and was dominant interspecific competition. In Jianghuai area and Huaibei plain, there were small covering of natural vegetation, different degree of degradation of ecological balance, few kinds of nectariferous plants with almost the same blooming periods, natural mating perturbed by Apis mellifera ligustica for Apis cerana cerana, and which was inferior in interspecific competition, colony size sharply decreased, distribution area reduced, and density cut down to a great extent. In Huaibei plain, the negative factors were more conspicuous.

Collective Memories of Portuguese Colonial Action in Africa: Representations of the Colonial Past among Mozambicans and Portuguese Youths

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João Feijó

2010-05-01

Full Text Available Social representations of the colonization and decolonization processes among young people from a former European colonial power (Portugal and from an African ex-colony (Mozambique were investigated through surveys using open- and closed-ended questions about national history, focusing on the identity functions of collective memories. Hegemonic and contested representations were found of the most prominent events related to Portuguese colonization of Mozambique, arousing a range of collective emotions. A central place is occupied by memories of the Colonial War, which ended with the Carnation Revolution in Portugal and the subsequent independence of the Portuguese African colonies. Overall, the depiction of colonialism was more negative for Mozambican than for Portuguese participants. The violent effects of colonial action were very salient in Mozambican memories, which stressed the most oppressive aspects of the colonial period, associated with slave trade and brutal repression. On the Portuguese side, the idealization of the voyages of discovery persisted, obscuring the most violent effects of colonial expansion. However, collective memories of colonization of former colonizer and former colonized do not simply stand opposed. Both Mozambican and Portuguese participants reported ambivalent feelings towards the colonization process.

SigB is a dominant regulator of virulence in Staphylococcus aureus small-colony variants.

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Mitchell, Gabriel; Fugère, Alexandre; Pépin Gaudreau, Karine; Brouillette, Eric; Frost, Eric H; Cantin, André M; Malouin, François

2013-01-01

Staphylococcus aureus small-colony variants (SCVs) are persistent pathogenic bacteria characterized by slow growth and, for many of these strains, an increased ability to form biofilms and to persist within host cells. The virulence-associated gene expression profile of SCVs clearly differs from that of prototypical strains and is often influenced by SigB rather than by the agr system. One objective of this work was to confirm the role of SigB in the control of the expression of virulence factors involved in biofilm formation and intracellular persistence of SCVs. This study shows that extracellular proteins are involved in the formation of biofilm by three SCV strains, which, additionally, have a low biofilm-dispersing activity. It was determined that SigB activity modulates biofilm formation by strain SCV CF07-S and is dominant over that of the agr system without being solely responsible for the repression of proteolytic activity. On the other hand, the expression of fnbA and the control of nuclease activity contributed to the SigB-dependent formation of biofilm of this SCV strain. SigB was also required for the replication of CF07-S within epithelial cells and may be involved in the colonization of lungs by SCVs in a mouse infection model. This study methodically investigated SigB activity and associated mechanisms in the various aspects of SCV pathogenesis. Results confirm that SigB activity importantly influences the production of virulence factors, biofilm formation and intracellular persistence for some clinical SCV strains.

A Novel indole compound that inhibits Pseudomonas aeruginosa growth by targeting MreB is a substrate for MexAB-OprM.

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Robertson, Gregory T; Doyle, Timothy B; Du, Qun; Duncan, Leonard; Mdluli, Khisimuzi E; Lynch, A Simon

2007-10-01

Drug efflux systems contribute to the intrinsic resistance of Pseudomonas aeruginosa to many antibiotics and biocides and hamper research focused on the discovery and development of new antimicrobial agents targeted against this important opportunistic pathogen. Using a P. aeruginosa PAO1 derivative bearing deletions of opmH, encoding an outer membrane channel for efflux substrates, and four efflux pumps belonging to the resistance nodulation/cell division class including mexAB-oprM, we identified a small-molecule indole-class compound (CBR-4830) that is inhibitory to growth of this efflux-compromised strain. Genetic studies established MexAB-OprM as the principal pump for CBR-4830 and revealed MreB, a prokaryotic actin homolog, as the proximal cellular target of CBR-4830. Additional studies establish MreB as an essential protein in P. aeruginosa, and efflux-compromised strains treated with CBR-4830 transition to coccoid shape, consistent with MreB inhibition or depletion. Resistance genetics further suggest that CBR-4830 interacts with the putative ATP-binding pocket in MreB and demonstrate significant cross-resistance with A22, a structurally unrelated compound that has been shown to promote rapid dispersion of MreB filaments in vivo. Interestingly, however, ATP-dependent polymerization of purified recombinant P. aeruginosa MreB is blocked in vitro in a dose-dependent manner by CBR-4830 but not by A22. Neither compound exhibits significant inhibitory activity against mutant forms of MreB protein that bear mutations identified in CBR-4830-resistant strains. Finally, employing the strains and reagents prepared and characterized during the course of these studies, we have begun to investigate the ability of analogues of CBR-4830 to inhibit the growth of both efflux-proficient and efflux-compromised P. aeruginosa through specific inhibition of MreB function.

Early aggressive eradication therapy for intermittent Pseudomonas aeruginosa airway colonization in cystic fibrosis patients: 15 years experience

DEFF Research Database (Denmark)

Hansen, C.R.; Pressler, T.; Høiby, Niels

2008-01-01

BACKGROUND: Since 1989, CF-patients intermittently colonized with Pseudomonas aeruginosa have been treated with inhaled colistin and oral ciprofloxacin in the Copenhagen CF-centre. The study evaluates 15 years results of this treatment. METHODS: All isolates of P. aeruginosa from CF-patients inte......BACKGROUND: Since 1989, CF-patients intermittently colonized with Pseudomonas aeruginosa have been treated with inhaled colistin and oral ciprofloxacin in the Copenhagen CF-centre. The study evaluates 15 years results of this treatment. METHODS: All isolates of P. aeruginosa from CF......-patients intermittently colonized with P. aeruginosa from 1989 to 2003 were identified All anti-P. aeruginosa treatments were evaluated for antibiotics used, treatment duration, pseudomonas-free interval and development of chronic infection. All P. aeruginosa isolates were assessed for resistance and for non......-mucoid or mucoid phenotype. RESULTS: 146 CF-patients were included in the study (1106 patient-years). 99 patients had first ever isolate during the study period. Median observation time 7 years (0.1-14.9). 12 patients developed chronic infection. A Kaplan Meyer plot showed protection from chronic infection in up...

Staphylococcus aureus Alters Growth Activity, Autolysis, and Antibiotic Tolerance in a Human Host-Adapted Pseudomonas aeruginosa Lineage

DEFF Research Database (Denmark)

Frydenlund Michelsen, Charlotte; Christensen, Anne-Mette; Bojer, Martin Saxtorph

2014-01-01

Interactions among members of polymicrobial infections or between pathogens and the commensal flora may determine disease outcomes. Pseudomonas aeruginosa and Staphylococcus aureus are important opportunistic human pathogens and are both part of the polymicrobial infection communities in human...... hosts. In this study, we analyzed the in vitro interaction between S. aureus and a collection of P. aeruginosa isolates representing different evolutionary steps of a dominant lineage, DK2, that have evolved through decades of growth in chronically infected patients. While the early adapted P....... aeruginosa DK2 strains outcompeted S. aureus during coculture on agar plates, we found that later P. aeruginosa DK2 strains showed a commensal-like interaction, where S. aureus was not inhibited by P. aeruginosa and the growth activity of P. aeruginosa was enhanced in the presence of S. aureus. This effect...

Post-colonial identity in Greenland?

DEFF Research Database (Denmark)

Gad, Ulrik Pram

2009-01-01

could be furthered by bringing politics back in. Based on a discourse analysis of the Greenlandic debate on language, this paper makes three claims: First, the identity projects promoted in Greenland are based on an essentialist conception of identity. Secondly, Greenlandic identity discourse combines......In the gradual unravelling of Greenland’s colonial relationship to Denmark, an essentialist conceptualization of Greenlandic identity has played a significant role. However, both our scholarly understanding of post-colonial Greenlandic identity and the process towards independence for Greenland...... elements of traditional Inuit culture and elements of colonial modernity. Thirdly, monolingual Greenlanders are those with the most to gain from abandoning the dichotomy of essentialist identities. Strategically, the paper suggests a post-post-colonial Greenlandic identity as a means of avoiding...

A Pseudomonas aeruginosa toxin that hijacks the host ubiquitin proteolytic system.

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Jennifer M Bomberger

2011-03-01

Full Text Available Pseudomonas aeruginosa (P. aeruginosa is an opportunistic pathogen chronically infecting the lungs of patients with chronic obstructive pulmonary disease (COPD, pneumonia, cystic fibrosis (CF, and bronchiectasis. Cif (PA2934, a bacterial toxin secreted in outer membrane vesicles (OMV by P. aeruginosa, reduces CFTR-mediated chloride secretion by human airway epithelial cells, a key driving force for mucociliary clearance. The aim of this study was to investigate the mechanism whereby Cif reduces CFTR-mediated chloride secretion. Cif redirected endocytosed CFTR from recycling endosomes to lysosomes by stabilizing an inhibitory effect of G3BP1 on the deubiquitinating enzyme (DUB, USP10, thereby reducing USP10-mediated deubiquitination of CFTR and increasing the degradation of CFTR in lysosomes. This is the first example of a bacterial toxin that regulates the activity of a host DUB. These data suggest that the ability of P. aeruginosa to chronically infect the lungs of patients with COPD, pneumonia, CF, and bronchiectasis is due in part to the secretion of OMV containing Cif, which inhibits CFTR-mediated chloride secretion and thereby reduces the mucociliary clearance of pathogens.

Antiplasmid Potential of Kalanchoe blossfeldiana Against Multidrug ResistancePseudomonas aeruginosa

OpenAIRE

ZirakFaqe Ahmed Abdulrahman

2014-01-01

This study concerned with the isolation of Pseudomonas aeruginosa from various clinical cases in human which include (burn, wound and urine) that admitted to Emergency hospital and internal lab of teaching hospital in Erbil city. Forty isolates of P. aeruginosa from out of 120 samples were identified by using cultured, morphological and biochemical tests in addition to vitek machine. According to the resistance of the isolates to these antibiotics they showed variation in their resistance; th...

Anti-Pseudomonas aeruginosa IgY antibodies augment bacterial clearance in a murine pneumonia model

DEFF Research Database (Denmark)

Thomsen, K.; Christophersen, L.; Bjarnsholt, T.

2016-01-01

Background: Oral prophylactic therapy by gargling with pathogen-specific egg yolk immunoglobulins (IgY) may reduce the initial airway colonization with Pseudomonas aeruginosa in cystic fibrosis (CF) patients. IgY antibodies impart passive immunization and we investigated the effects of anti......-P. aeruginosa IgY antibodies on bacterial eradication in a murine pneumonia model. Methods: P. aeruginosa pneumonia was established in Balb/c mice and the effects of prophylactic IgY administration on lung bacteriology, clinical parameters and subsequent inflammation were compared to controls. Results......: Prophylactic administration of IgY antibodies targeting P. aeruginosa significantly reduced the bacterial burden by 2-log 24 h post-infection compared to controls and was accompanied by significantly reduced clinical symptom scores and successive inflammatory cytokine profile indicative of diminished lung...

Biosorption of uranium by Pseudomonas aeruginosa strain CSU: Characterization and comparison studies

International Nuclear Information System (INIS)

Hu, M.Z.C.; Norman, J.M.; Faison, B.D.; Reeves, M.E.

1996-01-01

Pseudomonas aeruginosa strain CSU, a nongenetically engineered bacterial strain known to bind dissolved hexavalent uranium (as UO 2 2+ and/or its cationic hydroxo complexes) was characterized with respect to its sorptive activity. The uranium biosorption equilibrium could be described by the Langmuir isotherm. The rate of uranium adsorption increased following permeabilization of the outer and/or cytoplasmic membrane by organic solvents such as acetone. P. aeruginosa CSU biomass was significantly more sorptive toward uranium than certain novel, patented biosorbents derived from algal or fungal biomass sources. P. aeruginosa CSU biomass was also competitive with commercial cation-exchange resins, particularly in the presence of dissolved transition metals. Uranium binding by P. aeruginosa CSU was clearly pH dependent. Uranium loading capacity increased with increasing pH under acidic conditions, presumably as a function of uranium speciation and due to the H + competition at some binding sites. Nevertheless, preliminary evidence suggests that this microorganism is also capable of binding anionic hexavalent uranium complexes. Ferric iron was a strong inhibitor of uranium binding to P. aeruginosa CSU biomass, and the presence of uranium also decreased the Fe 3+ loading when the biomass was not saturated with Fe 3+ . Thus, a two-state process in which iron and uranium are removed in consecutive steps was proposed for efficient use of the biomass as a biosorbent in uranium removal from mine wastewater, especially acidic leachates

Anti-infective properties of Lactobacillus fermentum against Staphylococcus aureus and Pseudomonas aeruginosa.

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Varma, Parvathi; Nisha, N; Dinesh, Kavitha R; Kumar, Anil V; Biswas, Raja

2011-01-01

Surgical wounds and implant-associated Staphylococcus aureus and Pseudomonas aeruginosa infections are often difficult to treat because of limited susceptibility of several of these strains to conventional antibiotics. As a result, there is a constant need for new alternative drugs. The aim of this study was to investigate the antimicrobial properties of Lactobacillus fermentum, a probiotic bacterium, which we have isolated from colonic biopsies. The inhibition of S. aureus and P. aeruginosa growth was evaluated by coincubating with L. fermentum strains. Growth inhibition was tested for several of their clinical isolates using agar well diffusion assays. For biofilm assay S. aureus and P. aeruginosa were grown on the glass slides and in 96-well plates in presence of 2.5 μg/ml culture filtrate of L. fermentum. Biofilms were photographed using confocal microscope or stained with 0.1% crystal violet. Reduction in the cytotoxicity of S. aureus and P. aeruginosa was observed in presence of 2.5 μg/ml L. fermentum-spent media. Using in vitroexperiments, we showed that L. fermentum-secreted compound(s) inhibits the growth, cytotoxicity and biofilm formation of several S. aureus and P. aeruginosa strains. Compound(s) present in the culture supernatant of L. fermentum may have promising applications in treating hospital-acquired infections. Copyright © 2011 S. Karger AG, Basel.

C-di-GMP regulates antimicrobial peptide resistance in Pseudomonas aeruginosa

DEFF Research Database (Denmark)

Chua, Song Lin; Tan, Sean Yang-Yi; Rybtke, Morten Theil

2013-01-01

Bis-(3'-5')-cyclic dimeric GMP (c-di-GMP) is an intracellular second messenger which controls the life styles of many bacteria. A high intracellular level of c-di-GMP induces a biofilm lifestyle, whereas a low intracellular level of c-di-GMP stimulates dispersal of biofilms and promotes...... a planktonic lifestyle. Here, we used expression of different reporters to show that planktonic cells (PCells), biofilm cells (BCells) and cells dispersed from biofilms (DCells) had distinct intracellular c-di-GMP levels. Proteomics analysis showed that the low intracellular c-di-GMP level of DCells induced...... the expression of proteins required for the virulence and development of antimicrobial peptide resistance in P. aeruginosa. In accordance, P. aeruginosa cells with low c-di-GMP levels were found to be more resistant to colistin than P. aeruginosa cells with high c-di-GMP levels. This contradicts the current...

Mitophagy confers resistance to siderophore-mediated killing by Pseudomonas aeruginosa.

Science.gov (United States)

Kirienko, Natalia V; Ausubel, Frederick M; Ruvkun, Gary

2015-02-10

In the arms race of bacterial pathogenesis, bacteria produce an array of toxins and virulence factors that disrupt core host processes. Hosts mitigate the ensuing damage by responding with immune countermeasures. The iron-binding siderophore pyoverdin is a key virulence mediator of the human pathogen Pseudomonas aeruginosa, but its pathogenic mechanism has not been established. Here we demonstrate that pyoverdin enters Caenorhabditis elegans and that it is sufficient to mediate host killing. Moreover, we show that iron chelation disrupts mitochondrial homeostasis and triggers mitophagy both in C. elegans and mammalian cells. Finally, we show that mitophagy provides protection both against the extracellular pathogen P. aeruginosa and to treatment with a xenobiotic chelator, phenanthroline, in C. elegans. Although autophagic machinery has been shown to target intracellular bacteria for degradation (a process known as xenophagy), our report establishes a role for authentic mitochondrial autophagy in the innate immune defense against P. aeruginosa.

Hospital costs of nosocomial multi-drug resistant Pseudomonas aeruginosa acquisition

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Morales Eva

2012-05-01

Full Text Available Abstract Background We aimed to assess the hospital economic costs of nosocomial multi-drug resistant Pseudomonas aeruginosa acquisition. Methods A retrospective study of all hospital admissions between January 1, 2005, and December 31, 2006 was carried out in a 420-bed, urban, tertiary-care teaching hospital in Barcelona (Spain. All patients with a first positive clinical culture for P. aeruginosa more than 48 h after admission were included. Patient and hospitalization characteristics were collected from hospital and microbiology laboratory computerized records. According to antibiotic susceptibility, isolates were classified as non-resistant, resistant and multi-drug resistant. Cost estimation was based on a full-costing cost accounting system and on the criteria of clinical Activity-Based Costing methods. Multivariate analyses were performed using generalized linear models of log-transformed costs. Results Cost estimations were available for 402 nosocomial incident P. aeruginosa positive cultures. Their distribution by antibiotic susceptibility pattern was 37.1% non-resistant, 29.6% resistant and 33.3% multi-drug resistant. The total mean economic cost per admission of patients with multi-drug resistant P. aeruginosa strains was higher than that for non-resistant strains (15,265 vs. 4,933 Euros. In multivariate analysis, resistant and multi-drug resistant strains were independently predictive of an increased hospital total cost in compared with non-resistant strains (the incremental increase in total hospital cost was more than 1.37-fold and 1.77-fold that for non-resistant strains, respectively. Conclusions P. aeruginosa multi-drug resistance independently predicted higher hospital costs with a more than 70% increase per admission compared with non-resistant strains. Prevention of the nosocomial emergence and spread of antimicrobial resistant microorganisms is essential to limit the strong economic impact.

Comparative In Vitro Efficacy of Doripenem and Imipenem Against Multi-Drug Resistant Pseudomonas aeruginosa.

Science.gov (United States)

Wali, Nadia; Mirza, Irfan Ali

2016-04-01

To compare the in vitro efficacy of doripenem and imipenem against multi-drug resistant (MDR) Pseudomonas aeruginosa from various clinical specimens. Descriptive cross-sectional study. Department of Microbiology, Armed Forces Institute of Pathology, Rawalpindi, from November 2012 to November 2013. MDR Pseudomonas aeruginosa isolates from various clinical samples were included in the study. Susceptibility of Pseudomonas aeruginosa against doripenem and imipenem was performed by E-test strip and agar dilution methods. The results were interpreted as recommended by Clinical Laboratory Standard Institute (CLSI) guidelines. The maximum number of Pseudomonas aeruginosa were isolated from pure pus and pus swabs. In vitro efficacy of doripenem was found to be more effective as compared to imipenem against MDR Pseudomonas aeruginosa with both E-test strip and agar dilution methods. Overall, p-values of 0.014 and 0.037 were observed when susceptibility patterns of doripenem and imipenem were evaluated with E-test strip and agar dilution methods. In vitro efficacy of doripenem was found to be better against MDR Pseudomonas aeruginosaas compared to imipenem when tested by both E-test and agar dilution methods.

SERS detection of the biomarker hydrogen cyanide from Pseudomonas aeruginosa cultures isolated from cystic fibrosis patients

Science.gov (United States)

Lauridsen, Rikke Kragh; Sommer, Lea M.; Johansen, Helle Krogh; Rindzevicius, Tomas; Molin, Søren; Jelsbak, Lars; Engelsen, Søren Balling; Boisen, Anja

2017-03-01

Pseudomonas aeruginosa is the primary cause of chronic airway infections in cystic fibrosis (CF) patients. Persistent infections are seen from the first P. aeruginosa culture in about 75% of young CF patients, and it is important to discover new ways to detect P. aeruginosa at an earlier stage. The P. aeruginosa biomarker hydrogen cyanide (HCN) contains a triple bond, which is utilized in this study because of the resulting characteristic C≡N peak at 2135 cm-1 in a Raman spectrum. The Raman signal was enhanced by surface-enhanced Raman spectroscopy (SERS) on a Au-coated SERS substrate. After long-term infection, a mutation in the patho-adaptive lasR gene can alter the expression of HCN, which is why it is sometimes not possible to detect HCN in the breath of chronically infected patients. Four P. aeruginosa reference strains and 12 clinical P. aeruginosa strains isolated from CF children were evaluated, and HCN was clearly detected from overnight cultures of all wild type-like isolates and half of the later isolates from the same patients. The clinical impact could be that P. aeruginosa infections could be detected at an earlier stage, because daily breath sampling with an immediate output could be possible with a point-of-care SERS device.

Impedimetric quantification of the formation process and the chemosensitivity of cancer cell colonies suspended in 3D environment.

Science.gov (United States)

Lei, Kin Fong; Wu, Zong-Ming; Huang, Chia-Hao

2015-12-15

In cancer research, colony formation assay is a gold standard for the investigation of the development of early tumors and the effects of cytotoxic agents on tumors in vitro. Quantification of cancer cell colonies suspended in hydrogel is currently achieved by manual counting under microscope. It is challenging to microscopically quantify the colony number and size without subjective bias. In this work, impedimetric quantification of cancer cell colonies suspended in hydrogel was successfully developed and provides a quantitative and objective method to describe the colony formation process and the development of colony size during the culture course. A biosensor embedded with a pair of parallel plate electrodes was fabricated for the impedimetric quantification. Cancer cell (cell line: Huh-7) were encapsulated in methyl cellulose hydrogel and cultured to gradually form cancer cell colonies suspended in 3D environment. At pre-set schedule during the culture course, small volume (50 μL) of colonies/MC hydrogel was collected, mixed with measurement hydrogel, and loaded to the biosensor for measurement. Hence, the colony formation process could be quantitatively represented by a colony index and a colony size index calculated from electrical impedance. Based on these developments, chemosensitivity of cancer cell colonies under different concentrations of anti-cancer drug, i.e., doxorubicin, was quantitatively investigated to study the efficacy of anti-cancer drug. Also, dose-response curve was constructed to calculate the IC50 value, which is an important indicator for chemosensitivity assay. These results showed the impedimetric quantification is a promising technique for the colony formation assay. Copyright © 2015 Elsevier B.V. All rights reserved.

Early Developmental Program Shapes Colony Morphology in Bacteria

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Gideon Mamou

2016-03-01

Full Text Available When grown on a solid surface, bacteria form highly organized colonies, yet little is known about the earliest stages of colony establishment. Following Bacillus subtilis colony development from a single progenitor cell, a sequence of highly ordered spatiotemporal events was revealed. Colony was initiated by the formation of leading-cell chains, deriving from the colony center and extending in multiple directions, typically in a “Y-shaped” structure. By eradicating particular cells during these early stages, we could influence the shape of the resulting colony and demonstrate that Y-arm extension defines colony size. A mutant in ymdB encoding a phosphodiesterase displayed unordered developmental patterns, indicating a role in guiding these initial events. Finally, we provide evidence that intercellular nanotubes contribute to proper colony formation. In summary, we reveal a “construction plan” for building a colony and provide the initial molecular basis for this process.

Distinct pathogenesis and host responses during infection of C. elegans by P. aeruginosa and S. aureus.

Science.gov (United States)

Irazoqui, Javier E; Troemel, Emily R; Feinbaum, Rhonda L; Luhachack, Lyly G; Cezairliyan, Brent O; Ausubel, Frederick M

2010-07-01

The genetically tractable model host Caenorhabditis elegans provides a valuable tool to dissect host-microbe interactions in vivo. Pseudomonas aeruginosa and Staphylococcus aureus utilize virulence factors involved in human disease to infect and kill C. elegans. Despite much progress, virtually nothing is known regarding the cytopathology of infection and the proximate causes of nematode death. Using light and electron microscopy, we found that P. aeruginosa infection entails intestinal distention, accumulation of an unidentified extracellular matrix and P. aeruginosa-synthesized outer membrane vesicles in the gut lumen and on the apical surface of intestinal cells, the appearance of abnormal autophagosomes inside intestinal cells, and P. aeruginosa intracellular invasion of C. elegans. Importantly, heat-killed P. aeruginosa fails to elicit a significant host response, suggesting that the C. elegans response to P. aeruginosa is activated either by heat-labile signals or pathogen-induced damage. In contrast, S. aureus infection causes enterocyte effacement, intestinal epithelium destruction, and complete degradation of internal organs. S. aureus activates a strong transcriptional response in C. elegans intestinal epithelial cells, which aids host survival during infection and shares elements with human innate responses. The C. elegans genes induced in response to S. aureus are mostly distinct from those induced by P. aeruginosa. In contrast to P. aeruginosa, heat-killed S. aureus activates a similar response as live S. aureus, which appears to be independent of the single C. elegans Toll-Like Receptor (TLR) protein. These data suggest that the host response to S. aureus is possibly mediated by pathogen-associated molecular patterns (PAMPs). Because our data suggest that neither the P. aeruginosa nor the S. aureus-triggered response requires canonical TLR signaling, they imply the existence of unidentified mechanisms for pathogen detection in C. elegans, with

Distinct pathogenesis and host responses during infection of C. elegans by P. aeruginosa and S. aureus.

Directory of Open Access Journals (Sweden)

Javier E Irazoqui

2010-07-01

Full Text Available The genetically tractable model host Caenorhabditis elegans provides a valuable tool to dissect host-microbe interactions in vivo. Pseudomonas aeruginosa and Staphylococcus aureus utilize virulence factors involved in human disease to infect and kill C. elegans. Despite much progress, virtually nothing is known regarding the cytopathology of infection and the proximate causes of nematode death. Using light and electron microscopy, we found that P. aeruginosa infection entails intestinal distention, accumulation of an unidentified extracellular matrix and P. aeruginosa-synthesized outer membrane vesicles in the gut lumen and on the apical surface of intestinal cells, the appearance of abnormal autophagosomes inside intestinal cells, and P. aeruginosa intracellular invasion of C. elegans. Importantly, heat-killed P. aeruginosa fails to elicit a significant host response, suggesting that the C. elegans response to P. aeruginosa is activated either by heat-labile signals or pathogen-induced damage. In contrast, S. aureus infection causes enterocyte effacement, intestinal epithelium destruction, and complete degradation of internal organs. S. aureus activates a strong transcriptional response in C. elegans intestinal epithelial cells, which aids host survival during infection and shares elements with human innate responses. The C. elegans genes induced in response to S. aureus are mostly distinct from those induced by P. aeruginosa. In contrast to P. aeruginosa, heat-killed S. aureus activates a similar response as live S. aureus, which appears to be independent of the single C. elegans Toll-Like Receptor (TLR protein. These data suggest that the host response to S. aureus is possibly mediated by pathogen-associated molecular patterns (PAMPs. Because our data suggest that neither the P. aeruginosa nor the S. aureus-triggered response requires canonical TLR signaling, they imply the existence of unidentified mechanisms for pathogen detection in C

Subinhibitory concentration of kanamycin induces the Pseudomonas aeruginosa type VI secretion system.

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Cerith Jones

Full Text Available Pseudomonas aeruginosa is a Gram-negative bacterium found in natural environments including plants, soils and warm moist surfaces. This organism is also in the top ten of nosocomial pathogens, and prevalent in cystic fibrosis (CF lung infections. The ability of P. aeruginosa to colonize a wide variety of environments in a lasting manner is associated with the formation of a resistant biofilm and the capacity to efficiently outcompete other microorganisms. Here we demonstrate that sub-inhibitory concentration of kanamycin not only induces biofilm formation but also induces expression of the type VI secretion genes in the H1-T6SS cluster. The H1-T6SS is known for its role in toxin production and bacterial competition. We show that the antibiotic induction of the H1-T6SS only occurs when a functional Gac/Rsm pathway is present. These observations may contribute to understand how P. aeruginosa responds to antibiotic producing competitors. It also suggests that improper antibiotic therapy may enhance P. aeruginosa colonization, including in the airways of CF patients.

The impact of Great Cormorants on biogenic pollution of land ecosystems: Stable isotope signatures in small mammals

International Nuclear Information System (INIS)

Balčiauskas, Linas; Skipitytė, Raminta; Jasiulionis, Marius; Trakimas, Giedrius; Balčiauskienė, Laima; Remeikis, Vidmantas

2016-01-01

Studying the isotopic composition of the hair of two rodent species trapped in the territories of Great Cormorant colonies, we aimed to show that Great Cormorants transfer biogens from aquatic ecosystems to terrestrial ecosystems, and that these substances reach small mammals through the trophic cascade, thus influencing the nutrient balance in the terrestrial ecosystem. Analysis of δ"1"3C and δ"1"5N was performed on two dominant species of small mammals, Apodemus flavicollis and Myodes glareolus, inhabiting the territories of the colonies. For both species, the values of δ"1"3C and δ"1"5N were higher in the animals trapped in the territories of the colonies than those in control territories. In the hair of A. flavicollis and M. glareolus, the highest values of δ"1"5N (16.31 ± 3.01‰ and 17.86 ± 2.76‰, respectively) were determined in those animals trapped in the biggest Great Cormorant colony. δ"1"5N values were age dependent, highest in adult A. flavicollis and M. glareolus and lowest in juvenile animals. For δ"1"3C values, age-dependent differences were not registered. δ"1"5N values in both small mammal species from the biggest Great Cormorant colony show direct dependence on the intensity of influence. Biogenic pollution is at its strongest in the territories of the colonies with nests, significantly diminishing in the ecotones of the colonies and further in the control zones, where the influence of birds is negligible. Thus, Great Cormorant colonies alter ecosystem functioning by enrichment with biogens, with stable isotope values in small mammals significantly higher in the affected territories. - Highlights: • Cormorants transport nutrients from water to land ecosystems and pollute biogenically. • We studied stable isotope composition of small mammal hair in 3 cormorant colonies. • δ"1"3C and δ"1"5N were measured using elemental analyzer–isotope ratio mass spectrometer. • δ"1"3C and δ"1"5N values were higher in rodents inhabiting

The impact of Great Cormorants on biogenic pollution of land ecosystems: Stable isotope signatures in small mammals

Energy Technology Data Exchange (ETDEWEB)

Balčiauskas, Linas, E-mail: linasbal@ekoi.lt [Nature Research Centre, Akademijos 2, LT-08412 Vilnius (Lithuania); Skipitytė, Raminta, E-mail: raminta.skipityte@ftmc.lt [Nature Research Centre, Akademijos 2, LT-08412 Vilnius (Lithuania); Center for Physical Sciences and Technology, Savanorių 231, LT-02300 Vilnius (Lithuania); Jasiulionis, Marius, E-mail: mjasiulionis@ekoi.lt [Nature Research Centre, Akademijos 2, LT-08412 Vilnius (Lithuania); Trakimas, Giedrius, E-mail: giedrius.trakimas@gf.vu.lt [Center for Ecology and Environmental Research, Vilnius University, Vilnius (Lithuania); Institute of Life Sciences and Technology, Daugavpils University, Parades Str. 1a, Daugavpils, LV-5401 (Latvia); Balčiauskienė, Laima, E-mail: laiba@ekoi.lt [Nature Research Centre, Akademijos 2, LT-08412 Vilnius (Lithuania); Remeikis, Vidmantas, E-mail: vidrem@fi.lt [Center for Physical Sciences and Technology, Savanorių 231, LT-02300 Vilnius (Lithuania)

2016-09-15

Studying the isotopic composition of the hair of two rodent species trapped in the territories of Great Cormorant colonies, we aimed to show that Great Cormorants transfer biogens from aquatic ecosystems to terrestrial ecosystems, and that these substances reach small mammals through the trophic cascade, thus influencing the nutrient balance in the terrestrial ecosystem. Analysis of δ{sup 13}C and δ{sup 15}N was performed on two dominant species of small mammals, Apodemus flavicollis and Myodes glareolus, inhabiting the territories of the colonies. For both species, the values of δ{sup 13}C and δ{sup 15}N were higher in the animals trapped in the territories of the colonies than those in control territories. In the hair of A. flavicollis and M. glareolus, the highest values of δ{sup 15}N (16.31 ± 3.01‰ and 17.86 ± 2.76‰, respectively) were determined in those animals trapped in the biggest Great Cormorant colony. δ{sup 15}N values were age dependent, highest in adult A. flavicollis and M. glareolus and lowest in juvenile animals. For δ{sup 13}C values, age-dependent differences were not registered. δ{sup 15}N values in both small mammal species from the biggest Great Cormorant colony show direct dependence on the intensity of influence. Biogenic pollution is at its strongest in the territories of the colonies with nests, significantly diminishing in the ecotones of the colonies and further in the control zones, where the influence of birds is negligible. Thus, Great Cormorant colonies alter ecosystem functioning by enrichment with biogens, with stable isotope values in small mammals significantly higher in the affected territories. - Highlights: • Cormorants transport nutrients from water to land ecosystems and pollute biogenically. • We studied stable isotope composition of small mammal hair in 3 cormorant colonies. • δ{sup 13}C and δ{sup 15}N were measured using elemental analyzer–isotope ratio mass spectrometer. • δ{sup 13}C and �

Evaluation of Enoyl-Acyl Carrier Protein Reductase Inhibitors as Pseudomonas aeruginosa Quorum-Quenching Reagents

DEFF Research Database (Denmark)

Yang, Liang; Liu, Yang; Sternberg, Claus

2010-01-01

Pseudomonas aeruginosa is an opportunistic pathogen which is responsible for a wide range of infections. Production of virulence factors and biofilm formation by P. aeruginosa are partly regulated by cell-to-cell communication quorum-sensing systems. Identification of quorum-quenching reagents...... which block the quorum-sensing process can facilitate development of novel treatment strategies for P. aeruginosa infections. We have used molecular dynamics simulation and experimental studies to elucidate the efficiencies of two potential quorum-quenching reagents, triclosan and green tea...... epigallocatechin gallate (EGCG), which both function as inhibitors of the enoyl-acyl carrier protein (ACP) reductase (ENR) from the bacterial type II fatty acid synthesis pathway. Our studies suggest that EGCG has a higher binding affinity towards ENR of P. aeruginosa and is an efficient quorum-quenching reagent...

Molecular cloning and characterization of the recA gene of Pseudomonas aeruginosa PAO

Energy Technology Data Exchange (ETDEWEB)

Kokjohn, T.A.; Miller, R.V.

1985-08-01

The recA gene of Pseudomonas aeruginosa PAO has been isolated and introduced into Escherichia coli K-12. Resistance to killing by UV irradiation was restored in several RecA-E. coli K-12 hosts by the P. aeruginosa gene, as was resistance to methyl methanesulfonate. Recombination proficiency was also restored, as measured by HfrH-mediated conjugation and by the ability to propagate Fec-phage lambda derivatives. The cloned P. aeruginosa recA gene restored both spontaneous and mitomycin C-stimulated induction of lambda prophage in lysogens of a recA strain of E. coli K-12.

Garlic blocks quorum sensing and promotes rapid clearing of pulmonary Pseudomonas aeruginosa infections

DEFF Research Database (Denmark)

Bjarnsholt, Thomas; Jensen, P. Ø.; Rasmussen, Thomas Bovbjerg

2005-01-01

The opportunistic human pathogen Pseudomonas aeruginosa is the predominant micro-organism of chronic lung infections in cystic fibrosis patients. P. aeruginosa colonizes the lungs by forming biofilm microcolonies throughout the lung. Quorum sensing (QS) renders the biofilm bacteria highly tolerant......-treated biofilm. Garlic extract was administered as treatment for a mouse pulmonary infection model. Mice were treated with garlic extract or placebo for 7 days, with the initial 2 days being prophylactic before P. aeruginosa was instilled in the left lung of the mice. Bacteriology, mortality, histopathology...... and phagocytosis by PMNs, as well as leading to an improved outcome of pulmonary infections....

An American termite in Paris: temporal colony dynamics.

Science.gov (United States)

Baudouin, Guillaume; Dedeine, Franck; Bech, Nicolas; Bankhead-Dronnet, Stéphanie; Dupont, Simon; Bagnères, Anne-Geneviève

2017-12-01

Termites of the genus Reticulitermes are widespread invaders, particularly in urban habitats. Their cryptic and subterranean lifestyle makes them difficult to detect, and we know little about their colony dynamics over time. In this study we examined the persistence of Reticulitermes flavipes (Kollar) colonies in the city of Paris over a period of 15 years. The aim was (1) to define the boundaries of colonies sampled within the same four areas over two sampling periods, (2) to determine whether the colonies identified during the first sampling period persisted to the second sampling period, and (3) to compare the results obtained when colonies were delineated using a standard population genetic approach versus a Bayesian clustering method that combined both spatial and genetic information. Herein, colony delineations were inferred from genetic differences at nine microsatellite loci and one mitochondrial locus. Four of the 18 identified colonies did not show significant differences in their genotype distributions between the two sampling periods. While allelic richness was low, making it hard to reliably distinguish colony family type, most colonies appeared to retain the same breeding structure over time. These large and expansive colonies showed an important ability to fuse (39% were mixed-family colonies), contained hundreds of reproductives and displayed evidence of isolation-by-distance, suggesting budding dispersal. These traits, which favor colony persistence over time, present a challenge for pest control efforts, which apply treatment locally. The other colonies showed significant differences, but we cannot exclude the possibility that their genotype distributions simply changed over time.

Azithromycin blocks quorum sensing and alginate polymer formation and increases the sensitivity to serum and stationary growth phase killing of P. aeruginosa and attenuates chronic P. aeruginosa lung infection in Cftr -/--mice

DEFF Research Database (Denmark)

Hoffmann, N.; Lee, Bao le ri; Hentzer, Morten

2007-01-01

The consequences of O-acetylated alginate-producing Pseudomonas aeruginosa biofilms in the lungs of chronically infected cystic fibrosis (CF) patients are tolerance to both antibiotic treatments and effects on the innate and the adaptive defense mechanisms. In clinical trials, azithromycin (AZM...... and the complement system. Moreover, we show that AZM may affect the polymerization of P. aeruginosa alginate by the incomplete precipitation of polymerized alginate and high levels of readily dialyzable uronic acids. In addition, we find that mucoid bacteria in the stationary growth phase became sensitive to AZM......, whereas cells in the exponential phase did not. Interestingly, AZM-treated P. aeruginosa lasI mutants appeared to be particularly resistant to serum, whereas bacteria with a functional QS system did not. We show in a CF mouse model of chronic P. aeruginosa lung infection that AZM treatment results...

Characterization of Pseudomonas aeruginosa chitinase, a gradually secreted protein.

Science.gov (United States)

Folders, J; Algra, J; Roelofs, M S; van Loon, L C; Tommassen, J; Bitter, W

2001-12-01

The gram-negative bacterium Pseudomonas aeruginosa secretes many proteins into its extracellular environment via the type I, II, and III secretion systems. In this study, a gene, chiC, coding for an extracellular chitinolytic enzyme, was identified. The chiC gene encodes a polypeptide of 483 amino acid residues, without a typical N-terminal signal sequence. Nevertheless, an N-terminal segment of 11 residues was found to be cleaved off in the secreted protein. The protein shows sequence similarity to the secreted chitinases ChiC of Serratia marcescens, ChiA of Vibrio harveyi, and ChiD of Bacillus circulans and consists of an activity domain and a chitin-binding domain, which are separated by a fibronectin type III domain. ChiC was able to bind and degrade colloidal chitin and was active on the artificial substrates carboxymethyl-chitin-Remazol Brilliant Violet and p-nitrophenyl-beta-D-N,N',N"-triacetylchitotriose, but not on p-nitrophenyl-beta-D-N-acetylglucosamine, indicating that it is an endochitinase. Expression of the chiC gene appears to be regulated by the quorum-sensing system of P. aeruginosa, since this gene was not expressed in a lasIR vsmI mutant. After overnight growth, the majority of the ChiC produced was found intracellularly, whereas only small amounts were detected in the culture medium. However, after several days, the cellular pool of ChiC was largely depleted, and the protein was found in the culture medium. This release could not be ascribed to cell lysis. Since ChiC did not appear to be secreted via any of the known secretion systems, a novel secretion pathway seems to be involved.

FpvA receptor involvement in pyoverdine biosynthesis in Pseudomonas aeruginosa.

Science.gov (United States)

Shen, Jiangsheng; Meldrum, Allison; Poole, Keith

2002-06-01

Alignment of the Pseudomonas aeruginosa ferric pyoverdine receptor, FpvA, with similar ferric-siderophore receptors revealed that the mature protein carries an extension of ca. 70 amino acids at its N terminus, an extension shared by the ferric pseudobactin receptors of P. putida. Deletion of fpvA from the chromosome of P. aeruginosa reduced pyoverdine production in this organism, as a result of a decline in expression of genes (e.g., pvdD) associated with the biosynthesis of the pyoverdine peptide moiety. Wild-type fpvA restored pvd expression in the mutant, thereby complementing its pyoverdine deficiency, although a deletion derivative of fpvA encoding a receptor lacking the N terminus of the mature protein did not. The truncated receptor was, however, functional in pyoverdine-mediated iron uptake, as evidenced by its ability to promote pyoverdine-dependent growth in an iron-restricted medium. These data are consistent with the idea that the N-terminal extension plays a role in FpvA-mediated pyoverdine biosynthesis in P. aeruginosa.

Crystal structure of secretory protein Hcp3 from Pseudomonas aeruginosa.

Science.gov (United States)

Osipiuk, Jerzy; Xu, Xiaohui; Cui, Hong; Savchenko, Alexei; Edwards, Aled; Joachimiak, Andrzej

2011-03-01

The Type VI secretion pathway transports proteins across the cell envelope of Gram-negative bacteria. Pseudomonas aeruginosa, an opportunistic Gram-negative bacterial pathogen infecting humans, uses the type VI secretion pathway to export specific effector proteins crucial for its pathogenesis. The HSI-I virulence locus encodes for several proteins that has been proposed to participate in protein transport including the Hcp1 protein, which forms hexameric rings that assemble into nanotubes in vitro. Two Hcp1 paralogues have been identified in the P. aeruginosa genome, Hsp2 and Hcp3. Here, we present the structure of the Hcp3 protein from P. aeruginosa. The overall structure of the monomer resembles Hcp1 despite the lack of amino-acid sequence similarity between the two proteins. The monomers assemble into hexamers similar to Hcp1. However, instead of forming nanotubes in head-to-tail mode like Hcp1, Hcp3 stacks its rings in head-to-head mode forming double-ring structures.

Generalized Growth of Estuarine, Household and Clinical Isolates of Pseudomonas aeruginosa

OpenAIRE

Kelly E. Diaz; Susanna K. Remold; Ogochukwu Onyiri; Maura Bozeman; Peter A. Raymond; Paul E. Turner; Paul E. Turner

2018-01-01

Pseudomonas aeruginosa is an opportunistic pathogen of particular concern to immune-compromised people, such as cystic fibrosis patients and burn victims. These bacteria grow in built environments including hospitals and households, and in natural environments such as rivers and estuaries. However, there is conflicting evidence whether recent environments like the human lung and open ocean affect P. aeruginosa growth performance in alternate environments. We hypothesized that bacteria recentl...

Activity of Bacteriophages in Removing Biofilms of Pseudomonas aeruginosa Isolates from Chronic Rhinosinusitis Patients

NARCIS (Netherlands)

Fong, Stephanie A.; Drilling, Amanda; Morales, Sandra; Cornet, Marjolein E.; Woodworth, Bradford A.; Fokkens, Wytske J.; Psaltis, Alkis J.; Vreugde, Sarah; Wormald, Peter-John

2017-01-01

Introduction:Pseudomonas aeruginosa infections are prevalent amongst chronic rhinosinusitis (CRS) sufferers. Many P. aeruginosa strains form biofilms, leading to treatment failure. Lytic bacteriophages (phages) are viruses that infect, replicate within, and lyse bacteria, causing bacterial death.

Evolutionary insight from whole-genome sequencing of Pseudomonas aeruginosa from cystic fibrosis patients

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Marvig, Rasmus Lykke; Madsen Sommer, Lea Mette; Jelsbak, Lars

2015-01-01

is suggested to be due to the large genetic repertoire of P. aeruginosa and its ability to genetically adapt to the host environment. Here, we review the recent work that has applied whole-genome sequencing to understand P. aeruginosa population genomics, within-host microevolution and diversity, mutational...

Genome-wide screen of Pseudomonas aeruginosa In Saccharomyces cerevisiae identifies new virulence factors

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Rafat eZrieq

2015-11-01

Full Text Available Pseudomonas aeruginosa is a human opportunistic pathogen that causes mortality in cystic fibrosis and immunocompromised patients. While many virulence factors of this pathogen have already been identified, several remain to be discovered. In this respect we set an unprecedented genome-wide screen of a P. aeruginosa expression library based on a yeast growth phenotype. 51 candidates were selected in a three-round screening process. The robustness of the screen was validated by the selection of three well known secreted proteins including one demonstrated virulence factor, the protease LepA. Further in silico sorting of the 51 candidates highlighted three potential new Pseudomonas effector candidates (Pec. By testing the cytotoxicity of wild type P. aeruginosa vs pec mutants towards macrophages and the virulence in the Caenorhabditis elegans model, we demonstrated that the three selected Pecs are novel virulence factors of P. aeruginosa. Additional cellular localization experiments in the host revealed specific localization for Pec1 and Pec2 that could inform about their respective functions.

Killing of Pseudomonas aeruginosa by Chicken Cathelicidin-2 Is Immunogenically Silent, Preventing Lung Inflammation In Vivo

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Coorens, Maarten; Banaschewski, Brandon J. H.; Baer, Brandon J.; Yamashita, Cory; van Dijk, Albert; Veldhuizen, Ruud A. W.; Veldhuizen, Edwin J. A.

2017-01-01

ABSTRACT The development of antibiotic resistance by Pseudomonas aeruginosa is a major concern in the treatment of bacterial pneumonia. In the search for novel anti-infective therapies, the chicken-derived peptide cathelicidin-2 (CATH-2) has emerged as a potential candidate, with strong broad-spectrum antimicrobial activity and the ability to limit inflammation by inhibiting Toll-like receptor 2 (TLR2) and TLR4 activation. However, as it is unknown how CATH-2 affects inflammation in vivo, we investigated how CATH-2-mediated killing of P. aeruginosa affects lung inflammation in a murine model. First, murine macrophages were used to determine whether CATH-2-mediated killing of P. aeruginosa reduced proinflammatory cytokine production in vitro. Next, a murine lung model was used to analyze how CATH-2-mediated killing of P. aeruginosa affects neutrophil and macrophage recruitment as well as cytokine/chemokine production in the lung. Our results show that CATH-2 kills P. aeruginosa in an immunogenically silent manner both in vitro and in vivo. Treatment with CATH-2-killed P. aeruginosa showed reduced neutrophil recruitment to the lung as well as inhibition of cytokine and chemokine production, compared to treatment with heat- or gentamicin-killed bacteria. Together, these results show the potential for CATH-2 as a dual-activity antibiotic in bacterial pneumonia, which can both kill P. aeruginosa and prevent excessive inflammation. PMID:28947647

Synthetic Peptides to Target Stringent Response-Controlled Virulence in a Pseudomonas aeruginosa Murine Cutaneous Infection Model

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Daniel Pletzer

2017-09-01

Full Text Available Microorganisms continuously monitor their surroundings and adaptively respond to environmental cues. One way to cope with various stress-related situations is through the activation of the stringent stress response pathway. In Pseudomonas aeruginosa this pathway is controlled and coordinated by the activity of the RelA and SpoT enzymes that metabolize the small nucleotide secondary messenger molecule (pppGpp. Intracellular ppGpp concentrations are crucial in mediating adaptive responses and virulence. Targeting this cellular stress response has recently been the focus of an alternative approach to fight antibiotic resistant bacteria. Here, we examined the role of the stringent response in the virulence of P. aeruginosa PAO1 and the Liverpool epidemic strain LESB58. A ΔrelA/ΔspoT double mutant showed decreased cytotoxicity toward human epithelial cells, exhibited reduced hemolytic activity, and caused down-regulation of the expression of the alkaline protease aprA gene in stringent response mutants grown on blood agar plates. Promoter fusions of relA or spoT to a bioluminescence reporter gene revealed that both genes were expressed during the formation of cutaneous abscesses in mice. Intriguingly, virulence was attenuated in vivo by the ΔrelA/ΔspoT double mutant, but not the relA mutant nor the ΔrelA/ΔspoT complemented with either gene. Treatment of a cutaneous P. aeruginosa PAO1 infection with anti-biofilm peptides increased animal welfare, decreased dermonecrotic lesion sizes, and reduced bacterial numbers recovered from abscesses, resembling the phenotype of the ΔrelA/ΔspoT infection. It was previously demonstrated by our lab that ppGpp could be targeted by synthetic peptides; here we demonstrated that spoT promoter activity was suppressed during cutaneous abscess formation by treatment with peptides DJK-5 and 1018, and that a peptide-treated relA complemented stringent response double mutant strain exhibited reduced peptide

A characterization of DNA release in Pseudomonas aeruginosa cultures and biofilms

DEFF Research Database (Denmark)

Allesen-Holm, Marie; Barken, Kim Bundvig; Yang, Liang

2006-01-01

-type P. aeruginosa biofilms stained with different DNA stains suggested that the extracellular DNA is located primarily in the stalks of mushroom-shaped multicellular structures, with a high concentration especially in the outer part of the stalks forming a border between the stalk-forming bacteria...... to whole-genome DNA. Evidence that the extracellular DNA in P. aeruginosa biofilms and cultures is generated via lysis of a subpopulation of the bacteria was obtained through experiments where extracellular beta-galactosidase released from lacZ-containing P. aeruginosa strains was assessed. Experiments...... and the cap-forming bacteria. Biofilms formed by lasIrhlI, pqsA and fliMpilA mutants contained less extracellular DNA than biofilms formed by the wild type, and the mutant biofilms were more susceptible to treatment with sodium dodecyl sulphate than the wild-type biofilm....

Pseudomoniasis phytotherapy: a review on most important Iranian medicinal plants effective on Pseudomonas aeruginosa.

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Bahmani, Mahmoud; Rafieian-Kopaei, Mahmoud; Hassanzadazar, Hassan; Taherikalani, Morovat

2016-10-01

Pseudomonas aeruginosa is a Gram-negative, aerobic bacterium found in water and soil. It is a normal flora in skin and gastrointestinal tract of human beings. P. aeruginosa as an opportunistic pathogen involved in nosocomial infections having multiple pathogenic factors and shows high rate of resistance to different antibiotics. The aim of this study was to identify the most important native medicinal plants of Iran effective on P. aeruginosa. All required information was obtained by searching keywords such as P. aeruginosa , medicinal plant extracts or essential oils in published articles in authentic scientific databases such as Science Direct, Wiley-Blackwell, Springer, Google scholar, Scientific Information Database (SID) and Magiran. According to the literature review, our results showed 12 different native medicinal plants were effective against P. aeruginosa in Iran including Eucalyptus camadulensis, Marticaria chamomilla, Ferula gummosa Boiss, Lawsonia inermis, Ocimumgra tissimum, Allium sativum, Satureja hortensis L, Satureja bachtiarica Bunge, Satureja khuzestanica (Jamzad), Thymus daenensis Celak, Thymus carmanicus Jalals and Camellia sinensis. Phytochemical analysis has shown that bioactive compounds of medicinal plants with their antioxidant and antimicrobial properties can be good alternatives for the synthetic medicines in food and drug industry.

Enterobacter aerogenes metabolites enhance Microcystis aeruginosa biomass recovery for sustainable bioflocculant and biohydrogen production.

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Xu, Liang; Zhou, Mo; Ju, Hanyu; Zhang, Zhenxing; Zhang, Jiquan; Sun, Caiyun

2018-04-07

We report a recycling bioresource involving harvesting of Microcystis aeruginosa using the bioflocculant (MBF-32) produced by Enterobacter aerogenes followed by the recovery of the harvested M. aeruginosa as the main substrate for the sustainable production of MBF-32 and biohydrogen. The experimental results indicate that the efficiency of bioflocculation exceeded 90% under optimal conditions. The harvested M. aeruginosa was further recycled as the main substrate for the supply of necessary elements. The highest yield (3.6±0.1g/L) of MBF-32 could be obtained from 20g/L of wet biomass of M. aeruginosa with an additional 20g/L of glucose as the extra carbon source. The highest yield of biohydrogen was 35mL of H 2 /g (dw) algal biomass, obtained from 20g/L of wet biomass of M. aeruginosa with an additional 10g/L of glycerol. Transcriptome analyses indicated that MBF-32 was mainly composed of polysaccharide and tyrosine/tryptophan proteins. Furthermore, NADH synthase and polysaccharide export-related genes were found to be up-regulated. Copyright © 2018 Elsevier B.V. All rights reserved.

Characterization of bacteriophages infecting clinical isolates of Pseudomonas aeruginosa stored in a culture collection

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C.C.S. Zanetti

2013-08-01

Full Text Available Some clinical isolates of Pseudomonas aeruginosa stored in our culture collection did not grow or grew poorly and showed lysis on the culture plates when removed from the collection and inoculated on MacConkey agar. One hypothesis was that bacteriophages had infected and killed those clinical isolates. To check the best storage conditions to maintain viable P. aeruginosa for a longer time, clinical isolates were stored at various temperatures and were grown monthly. We investigated the presence of phage in 10 clinical isolates of P. aeruginosa stored in our culture collection. Four strains of P. aeruginosa were infected by phages that were characterized by electron microscopy and isolated to assess their ability to infect. The best condition to maintain the viability of the strains during storage was in water at room temperature. Three Siphoviridae and two Myoviridae phages were visualized and characterized by morphology. We confirmed the presence of bacteriophages infecting clinical isolates, and their ability to infect and lyse alternative hosts. Strain PAO1, however, did not show lysis to any phage. Mucoid and multidrug resistant strains of P. aeruginosa showed lysis to 50% of the phages tested.

DEVONIAN RUGOSE CORALS FROM THE KARAKORUM MOUNTAINS (NORTHERN PAKISTAN

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STEFAN SCHRÖDER

2004-11-01

Full Text Available The Karakorum Block is regarded as a microplate of "Gondwanan" origin and was part of the Cimmerian continent ("Mega Lhasa" which rifted away from the northern margin of Gondwana during the Late Palaeozoic/Early Mesozoic. From the Northern Karakorum Range (Yarkhun and Karambar River Valleys: structurally belonging to the Northern Sedimentary Belt an Upper Givetian to Lower Frasnian rugose coral fauna of the Shogram Formation is described. The fauna is dominated by cosmopolitan genera such as Hexagonaria, Disphyllum, Macgeea and the Temnophyllum/Spinophyllum group, generally showing a geographically wide distribution, although being absent from the Eastern Americas Realm in the Upper Givetian/Lower Frasnian. Therefore its components are of little use for biogeographical deductions at sub-realm level, and in explaining the relation between the Karakorum Range and other Cimmerian crustal blocks. A remarkable exception is the first record of the genus Pseudopexiphyllum outside of Turkey, indicating a connection to the western part of the Cimmerides. On species level, the coral fauna of the Shogram Formation is characterized by the development of a diverse and rather unique fauna including about 35 taxa, that differs from the faunas known from neighbouring crustal blocks. So far, faunistic links to the Central Iranian Microcontinent (Yazd-, and Tabas-Block, the northwest Iranian Plate (Elburz, Central Pamir, the Lhasa Block and Western Qiangtang are not clear, and although each of these fragments are believed to be closely connected they were apparently not in direct contact during the Devonian. However, the Karakorum fauna is remarkably close to one known from the Helmand Block in Afghanistan, showing a very similar generic composition that includes numerous morphologically closely related, although not identical species. Accordingly, the restricted faunal exchange led to the development of new taxa. Distribution of the new species of Spinophyllum

Post-Colonial Theory and Action Research

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Jim Parsons

2011-02-01

Full Text Available This essay explores connections between post-colonial theory and action research. Post-colonial theory is committed to addressing the plague of colonialism. Action research, at its core, promises to problematize uncontested ‘colonial’ hegemonies of any form. Both post-colonial theory and action research engage dialogic, critically reflective and collaborative values to offer a fuller range of human wisdom. The authors contend that post-colonialism theory calls for justice and seeks to speak to social and psychological suffering, exploitation, violence and enslavement done to the powerless victims of colonization around the world by challenging the superiority of dominant perspectives and seeking to re-position and empower the marginalized and subordinated. In similar ways, action research works to eradicate oppression, powerlessness and worthlessness by affirming solidarity with the oppressed, helping humans move from passive to active and by fundamentally reshaping power. Because both post-colonial theory and action research position the insider or oppressed in an ethic of efficacy, it values community, relationships, communication and equality, and is committed to reciprocity, reflexivity and reflection. Thus, both hold the potential to help reconstruct conditions for a more democratic and just society

Post-Colonial Theory and Action Research

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Jim B. Parsons

2011-04-01

Full Text Available This essay explores connections between post-colonial theory and action research. Post-colonial theory is committed to addressing the plague of colonialism. Action research, at its core, promises to problematize uncontested ‘colonial’ hegemonies of any form. Both post-colonial theory and action research engage dialogic, critically reflective and collaborative values to offer a fuller range of human wisdom. The authors contend that post-colonialism theory calls for justice and seeks to speak to social and psychological suffering, exploitation, violence and enslavement done to the powerless victims of colonization around the world by challenging the superiority of dominant perspectives and seeking to re-position and empower the marginalized and subordinated. In similar ways, action research works to eradicate oppression, powerlessness and worthlessness by affirming solidarity with the oppressed, helping humans move from passive to active and by fundamentally reshaping power. Because both post-colonial theory and action research position the insider or oppressed in an ethic of efficacy, it values community, relationships, communication and equality, and is committed to reciprocity, reflexivity and reflection. Thus, both hold the potential to help reconstruct conditions for a more democratic and just society.

Quorum-sensing-regulated virulence factors in Pseudomonas aeruginosa are toxic to Lucilia sericata maggots

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Andersen, A S; Joergensen, B; Bjarnsholt, T

2010-01-01

Maggot debridement therapy (MDT) is widely used for debridement of chronic infected wounds; however, for wounds harbouring specific bacteria limited effect or failure of the treatment has been described. Here we studied the survival of Lucilia sericata maggots encountering Pseudomonas aeruginosa...... PAO1 in a simple assay with emphasis on the quorum-sensing (QS)-regulated virulence. The maggots were challenged with GFP-tagged P. aeruginosa wild-type (WT) PAO1 and a GFP-tagged P. aeruginosa DeltalasR rhlR (DeltaRR) QS-deficient mutant in different concentrations. Maggots were killed...

Colony variation of Helicobacter pylori: pathogenic potential is correlated to cell wall lipid composition.

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Bukholm, G; Tannaes, T; Nedenskov, P; Esbensen, Y; Grav, H J; Hovig, T; Ariansen, S; Guldvog, I

1997-05-01

Differences in expression of disease after infection with Helicobacter pylori have so far been connected with host factors and bacterial interstrain variation. In this study, spontaneous and ecology-mediated intrastrain variation was examined. Four clinical isolates of H. pylori were shown to give rise to two colony forms. Bacterial morphology was examined by electron microscopy. Bacterial fractions were examined for proteins using ion exchange chromatography and SDS-PAGE; for lipids using thin-layer chromatography, lipid anion-exchange chromatography, column chromatography on silica gel, 31P-NMR, gas chromatography and mass spectrometry. Bacterial in vitro invasiveness and adhesiveness were examined in two different systems, and urease and VacA toxin were assayed by Western blot analysis. H. pylori was shown to give rise to two colony forms: at normal pH the population was dominated by L colonies. One strain was chosen for further studies. Bacteria from L colonies retained VacA toxin and urease, did not invade or adhere to epithelial cells, and contained normal quantities of phosphatidylethanolamine. In a small frequency, spontaneous S colonies were formed. Bacteria from these colonies released VacA and urease, adhered to and invaded epithelial cells and contained increased amounts of lysophosphatidyl ethanolamine and phosphatidyl serine. After addition of HCl to the culture medium (pH6), almost only S colonies were formed. The results demonstrate that environmental factors, such as HCl, can change the bacterial cell wall, and thereby enhance expression of virulence factors of H. pylori in vitro. A similar in vivo variation would have implications for our understanding of the interaction between HCl secretion in the gastric mucosa and H. pylori in the development of peptic ulcer disease.

AMINOGLYCOSIDE RESISTANCE GENES IN Pseudomonas aeruginosa ISOLATES FROM CUMANA, VENEZUELA

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Bertinellys TEIXEIRA

2016-01-01

Full Text Available The enzymatic modification of aminoglycosides by aminoglycoside-acetyltransferases (AAC, aminoglycoside-adenyltransferases (AAD, and aminoglycoside-phosphotransferases (APH, is the most common resistance mechanism in P. aeruginosa and these enzymes can be coded on mobile genetic elements that contribute to their dispersion. One hundred and thirty seven P. aeruginosa isolates from the University Hospital, Cumana, Venezuela (HUAPA were evaluated. Antimicrobial susceptibility was determined by the disk diffusion method and theaac, aadB and aph genes were detected by PCR. Most of the P. aeruginosa isolates (33/137 were identified from the Intensive Care Unit (ICU, mainly from discharges (96/137. The frequency of resistant P. aeruginosaisolates was found to be higher for the aminoglycosides tobramycin and amikacin (30.7 and 29.9%, respectively. Phenotype VI, resistant to these antibiotics, was the most frequent (14/49, followed by phenotype I, resistant to all the aminoglycosides tested (12/49. The aac(6´-Ib,aphA1 and aadB genes were the most frequently detected, and the simultaneous presence of several resistance genes in the same isolate was demonstrated. Aminoglycoside resistance in isolates ofP. aeruginosa at the HUAPA is partly due to the presence of the aac(6´-Ib, aphA1 andaadB genes, but the high rates of antimicrobial resistance suggest the existence of several mechanisms acting together. This is the first report of aminoglycoside resistance genes in Venezuela and one of the few in Latin America.

AMINOGLYCOSIDE RESISTANCE GENES IN Pseudomonas aeruginosa ISOLATES FROM CUMANA, VENEZUELA.

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Teixeira, Bertinellys; Rodulfo, Hectorina; Carreño, Numirin; Guzmán, Militza; Salazar, Elsa; De Donato, Marcos

2016-01-01

The enzymatic modification of aminoglycosides by aminoglycoside-acetyltransferases (AAC), aminoglycoside-adenyltransferases (AAD), and aminoglycoside-phosphotransferases (APH), is the most common resistance mechanism in P. aeruginosa and these enzymes can be coded on mobile genetic elements that contribute to their dispersion. One hundred and thirty seven P. aeruginosa isolates from the University Hospital, Cumana, Venezuela (HUAPA) were evaluated. Antimicrobial susceptibility was determined by the disk diffusion method and theaac, aadB and aph genes were detected by PCR. Most of the P. aeruginosa isolates (33/137) were identified from the Intensive Care Unit (ICU), mainly from discharges (96/137). The frequency of resistant P. aeruginosaisolates was found to be higher for the aminoglycosides tobramycin and amikacin (30.7 and 29.9%, respectively). Phenotype VI, resistant to these antibiotics, was the most frequent (14/49), followed by phenotype I, resistant to all the aminoglycosides tested (12/49). The aac(6´)-Ib,aphA1 and aadB genes were the most frequently detected, and the simultaneous presence of several resistance genes in the same isolate was demonstrated. Aminoglycoside resistance in isolates ofP. aeruginosa at the HUAPA is partly due to the presence of the aac(6´)-Ib, aphA1 andaadB genes, but the high rates of antimicrobial resistance suggest the existence of several mechanisms acting together. This is the first report of aminoglycoside resistance genes in Venezuela and one of the few in Latin America.

Different Dose-Dependent Modes of Action of C-Type Natriuretic Peptide on Pseudomonas aeruginosa Biofilm Formation

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Florie Desriac

2018-04-01

Full Text Available We have previously shown that the C-type Natriuretic Peptide (CNP, a peptide produced by lungs, is able to impact Pseudomonas aeruginosa physiology. In the present work, the effect of CNP at different concentrations on P. aeruginosa biofilm formation was studied and the mechanisms of action of this human hormone on P. aeruginosa were deciphered. CNP was shown to inhibit dynamic biofilm formation in a dose-dependent manner without affecting the bacterial growth at any tested concentrations. The most effective concentrations were 1 and 0.1 µM. At 0.1 µM, the biofilm formation inhibition was fully dependent on the CNP sensor protein AmiC, whereas it was only partially AmiC-dependent at 1 µM, revealing the existence of a second AmiC-independent mode of action of CNP on P. aeruginosa. At 1 µM, CNP reduced both P. aeruginosa adhesion on glass and di-rhamnolipid production and also increased the bacterial membrane fluidity. The various effects of CNP at 1 µM and 0.1 µM on P. aeruginosa shown here should have major consequences to design drugs for biofilm treatment or prevention.

CHRISTIANITY AND COLONIALISM IN SOME ENGLISH SHORT STORIES

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Tatang Iskarna

2017-04-01

Full Text Available Colonial and postcolonial studies are often linked to the power domination of the West upon the East in the way that the East economically, politically, and socially oppressed. Colonialism is often associated with three elements, the explorers dealing with geographical information, missionaries approaching the local people culturally, and the colonial administrators ruling the colony. Gold, glory, and gospel are the European’s concern. However, in representing the relation between Christianity and colonialism there is critical dialectic amongst historians, anthropologists, Christian missions, or cultural critics. Some propose that Christianity is considered to be the religious arm of colonialism. Others state that Christianity is spread without any secular interest as it is a great commandment of Jesus Christ. A few believe that Christianity give critical resistance against colonialism. The relation between Christianity and colonialism cannot be simplified as being neutral, in complicity, or in opposition. So, it is worth-discussing to understand how European writers construct the relation between Christianity and colonialism in their literary work. How Christianity is constructed and how Christianity is related to colonialism will be discussed in this paper. Using postcolonial paradigm, two English short stories will be analyzed in that way. They are Rudyard Kipling’s “Lispeth” and Doris Lessing’s “No Witchcraft for Sale”.

Insights into the respiratory tract microbiota of patients with cystic fibrosis during early Pseudomonas aeruginosa colonization

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Keravec, Marlene; Mounier, Jerome; Prestat , Emmanuel; Vallet, Sophie; Jansson, Janet K.; Bergaud , Gaetaqn; Rosec, Silvain; Gourious, Stephanie; Rault, Gilles; Coton, Emmanuel; Barbier, George; Hery-Arnaud, Geneveieve

2015-08-09

Abstract Pseudomonas aeruginosa plays a major role in cystic fibrosis (CF) progression. Therefore, it is important to understand the initial steps of P. aeruginosa infection. The structure and dynamics of CF respiratory tract microbial communities during the early stages of P. aeruginosa colonization were characterized by pyrosequencing and cloning-sequencing. The respiratory microbiota showed high diversity, related to the young age of the CF cohort (mean age 10 years). Wide inter- and intra-individual variations were revealed. A common core microbiota of 5 phyla and 13 predominant genera was found, the majority of which were obligate anaerobes. A few genera were significantly more prevalent in patients never infected by P. aeruginosa. Persistence of an anaerobic core microbiota regardless of P. aeruginosa status suggests a major role of certain anaerobes in the pathophysiology of lung infections in CF. Some genera may be potential biomarkers of pulmonary infection state.

Disease in the Society: Infectious Cadavers Result in Collapse of Ant Sub-Colonies

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Loreto, Raquel G.; Hughes, David P.

2016-01-01

Despite the growing number of experimental studies on mechanisms of social immunity in ant societies, little is known about how social behavior relates to disease progression within the nests of ants. In fact, when empirically studying disease in ant societies, it is common to remove dead ants from experiments to confirm infection by the studied parasite. This unfortunately does not allow disease to progress within the nest as it may be assumed would happen under natural conditions. Therefore, the approach taken so far has resulted in a limited knowledge of diseases dynamics within the nest environment. Here we introduced a single infectious cadaver killed by the fungus Beauveria bassiana into small nests of the ant Camponotus castaneus. We then observed the natural progression of the disease by not removing the corpses of the ants that died following the first entry of the disease. Because some behaviors such as social isolation of sick individuals or the removal of cadavers by nestmates are considered social immune functions and thus adaptations at the colony level that reduce disease spread, we also experimentally confined some sub-colonies to one or two chamber nests to prevent the expression of such behaviors. Based on 51 small nests and survival studies in 1,003 ants we found that a single introduced infectious cadaver was able to transmit within the nest, and social immunity did not prevent the collapse of the small sub-colonies here tested. This was true whether ants did or did not have the option to remove the infectious cadaver. Therefore, we found no evidence that the typically studied social immunity behaviors can reduce disease spread in the conditions here tested. PMID:27529548

Branch to colony trajectory in a modular organism: pattern formation in the Indo-Pacific coral Stylophora pistillata.

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Shaish, Lee; Abelson, Avigdor; Rinkevich, Baruch

2006-08-01

The architecture of the colony in a branching coral is an iterative process in which new layers of calcium carbonate compile atop existing structures that remain unchanged. Colony growth and development, known as astogeny, is believed to be a continuous process, characterized by replication of lower rank unites, polyps, and branches. This study seeks to explore the genetic blueprint of branch-to-colony developmental trajectory in the branching coral Stylophora pistillata, within an astogeny period of 1 year. One hundred small branches (initially 2-4 cm long) were sampled from 10 colonies. A year later, 63 remaining colonies were analyzed for their architectural rules by using 15 morphometric parameters. Multivariate statistical tests were preformed. Cluster and two-dimensional nonmetric Multi-Dimensional Scaling analyses revealed that the 10 genotypes could be divided into two major morphometric groups and two intermediate groups, whereas SIMPER analyses (a similarity percentage test) on within-genet similarities showed high similarity between the ramets developed from each of the 10 genotypes. Although, at first, it seemed that different colonies exhibited variable and different architectural designs (each characterized by specific morphometric parameters), a comprehensive analysis revealed that all 10 coral genotypes exhibited a single common developmental plan that was characterized by a continuum of architectural design with several distinct stages. Each stage is marked by its own characteristic morphometric parameters. Changing of developmental rules during the trajectory from branch to coral colony may help the colony to cope better with environmental constraints.

Diversity of metabolic profiles of cystic fibrosis Pseudomonas aeruginosa during the early stages of lung infection

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Jørgensen, Karin Meinike; Wassermann, Tina; Johansen, Helle Krogh

2015-01-01

Pseudomonas aeruginosa is the dominant pathogen infecting the airways of cystic fibrosis (CF) patients. During the intermittent colonization phase, P. aeruginosa resembles environmental strains but later evolves to the chronic adapted phenotype characterized by resistance to antibiotics and mutat......Pseudomonas aeruginosa is the dominant pathogen infecting the airways of cystic fibrosis (CF) patients. During the intermittent colonization phase, P. aeruginosa resembles environmental strains but later evolves to the chronic adapted phenotype characterized by resistance to antibiotics...

The impact of nosocomially-acquired resistant Pseudomonas aeruginosa infection in a burn unit.

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Armour, Alexis D; Shankowsky, Heather A; Swanson, Todd; Lee, Jonathan; Tredget, Edward E

2007-07-01

Nosocomially-acquired Pseudomonas aeruginosa remains a serious cause of infection and septic mortality in burn patients. This study was conducted to quantify the impact of nosocomially-transmitted resistant P. aeruginosa in a burn population. Using a TRACS burn database, 48 patients with P. aeruginosa resistant to gentamicin were identified (Pseudomonas group). Thirty-nine were case-matched to controls without resistant P. aeruginosa cultures (control group) for age, total body surface area, admission year, and presence of inhalation injury. Mortality and various morbidity endpoints were examined, as well as antibiotic costs. There was a significantly higher mortality rate in the Pseudomonas group (33% vs. 8%, p products used (packed cells 51.1 +/- 8.0 vs. 21.1 +/- 3.4, p < 0.01; platelets 11.9 +/- 3.0 vs. 1.4 +/- 0.7, p < 0.01) were all significantly higher in the Pseudomonas group. Cost of antibiotics was also significantly higher ($2,658.52 +/- $647.93 vs. $829.22 +/- $152.82, p < 0.01). Nosocomial colonization or infection, or both, of burn patients with aminoglycoside-resistant P. aeruginosa is associated with significantly higher morbidity, mortality, and cost of care. Increased resource consumption did not prevent significantly higher mortality rates when compared with that of control patients. Thus, prevention, identification, and eradication of nosocomial Pseudomonas contamination are critical for cost-effective, successful burn care.

Glucocorticoids can affect Pseudomonas aeruginosa (ATCC 27853) internalization and intracellular calcium concentration in cystic fibrosis bronchial epithelial cells.

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Hussain, Rashida; Shahror, Rami; Karpati, Ferenc; Roomans, Godfried M

2015-01-01

Glucocorticoids (GCs) are anti-inflammatory agents, but their use in cystic fibrosis (CF) is controversial. In CF, the early colonization with Pseudomonas aeruginosa is mainly due to nonmucoid strains that can internalize, and induce apoptosis in the epithelial cells. Uptake of P. aeruginosa by the epithelial cells and subsequent apoptosis may prevent colonization of P. aeruginosa in CF airways. In the airway epithelia, several other biological effects, including an anti-secretory role by decreasing intracellular Ca(2+) concentration have been described for this anti-inflammatory drug. However, the effects of GCs on the nonmucoid P. aeruginosa internalization and intracellular Ca(2+) in CF bronchial epithelial cells have not been evaluated. We used cultured human CF bronchial airway epithelial cell (CFBE) monolayers to determine P. aeruginosa internalization, apoptosis, and intracellular Ca(2+)concentration in CF bronchial epithelial cells. Cells were treated with IL-6, IL-8, dexamethasone, betamethasone, or budesonide. GCs in co-treatments with IL-6 reversed the effect of IL-6 by decreasing the internalization of P. aeruginosa in the CFBE cells. GCs decreased the extent of apoptosis in CFBE cells infected with internalized P. aeruginosa, and increased the intracellular Ca(2+) concentration. These findings suggest that if internalization of P. aeruginosa reduces infection, GC therapy would increase the risk of pulmonary infection by decreasing the internalization of P. aeruginosa in CF cells, but GCs may improve airway hydration by increasing the intracellular Ca(2+) concentration. Whether the benefits of GC treatment outweigh the negative effects is questionable, and further clinical studies need to be carried out.

Neonicotinoid pesticides can reduce honeybee colony genetic diversity.

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Nadège Forfert

Full Text Available Neonicotinoid insecticides can cause a variety of adverse sub-lethal effects in bees. In social species such as the honeybee, Apis mellifera, queens are essential for reproduction and colony functioning. Therefore, any negative effect of these agricultural chemicals on the mating success of queens may have serious consequences for the fitness of the entire colony. Queens were exposed to the common neonicotinoid pesticides thiamethoxam and clothianidin during their developmental stage. After mating, their spermathecae were dissected to count the number of stored spermatozoa. Furthermore, their worker offspring were genotyped with DNA microsatellites to determine the number of matings and the genotypic composition of the colony. Colonies providing the male mating partners were also inferred. Both neonicotinoid and control queens mated with drones originating from the same drone source colonies, and stored similar number of spermatozoa. However, queens reared in colonies exposed to both neonicotinoids experienced fewer matings. This resulted in a reduction of the genetic diversity in their colonies (i.e. higher intracolonial relatedness. As decreased genetic diversity among worker bees is known to negatively affect colony vitality, neonicotinoids may have a cryptic effect on colony health by reducing the mating frequency of queens.

Dissemination of metallo-β-lactamase in Pseudomonas aeruginosa isolates in Egypt: mutation in blaVIM-4.

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Hashem, Hany; Hanora, Amro; Abdalla, Salah; Shaeky, Alaa; Saad, Alaa

2017-05-01

This study was designed to investigate the prevalence of metallo-β-lactamase (MBL) in Pseudomonas aeruginosa isolates collected from Suez Canal University Hospital in Ismailia, Egypt. Antibiotic susceptibility testing and phenotypic and genotypic screening for MBLs were performed on 147 isolates of P. aeruginosa. MICs were determined by agar dilution method for carbapenem that was ≥2 μg/mL for meropenem. MBL genes were detected by multiplex and monoplex PCR for P. aeruginosa-harbored plasmids. Mutation profile of sequenced MBL genes was screened using online software Clustal Omega. Out of 147 P. aeruginosa, 39 (26.5%) were carbapenem-resistant isolates and 25 (64%) were confirmed to be positive for MBLs. The susceptibility rate of P. aeruginosa toward polymyxin B and norfloxacin was 99% and 88%, respectively. Identification of collected isolates by API analysis and constructed phylogenetic tree of 16S rRNA showed that the isolates were related to P. aeruginosa species. The frequency of blaGIM-1, blaSIM-1, and blaSPM-1 was 52%, 48%, and 24%, respectively. BlaVIM and blaIMP-like genes were 20% and 4% and the sequences confirm the isolate to be blaVIM-1, blaVIM-2, blaVIM-4, and blaIMP-1. Three mutations were identified in blaVIM-4 gene. Our study emphasizes the high occurrence of multidrug-resistant P. aeruginosa-producing MBL enzymes. © 2017 APMIS. Published by John Wiley & Sons Ltd.

Resistance patterns of Pseudomonas aeruginosa isolated from HIV ...

African Journals Online (AJOL)

negative bacilli in patients with impaired host defences emphasizes the need for information on the antibiotic susceptibility of the organisms that infects such patients. Pseudomonas aeruginosa are becoming increasingly resistant to ...

Prevalence of Pseudomonas aeruginosa and Acinetobacter spp. in subgingival biofilm and saliva of subjects with chronic periodontal infection

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Renata Souto

2014-06-01

Full Text Available P. aeruginosa and Acinetobacter spp. are important pathogens associated with late nosocomial pneumonia in hospitalized and institutionalized individuals. The oral cavity may be a major source of these respiratory pathogens, particularly in the presence of poor oral hygiene and periodontal infection. This study investigated the prevalence of P. aeruginosa and Acinetobacter spp. in subgingival biofilm and saliva of subjects with periodontal disease or health. Samples were obtained from 55 periodontally healthy (PH and 169 chronic periodontitis (CP patients. DNA was obtained from the samples and detection of P. aeruginosa and Acinetobacter spp. was carried out by multiplex and nested PCR. P. aeruginosa and Acinetobacter spp. were detected in 40% and 45% of all samples, respectively. No significant differences in the distribution of these microorganisms between men and women, subgingival biofilm and saliva samples, patients 35 years of age, and smokers and non-smokers were observed regardless periodontal status (p > 0.05. In contrast, the frequencies of P. aeruginosa and Acinetobacter spp. in saliva and biofilm samples were significantly greater in CP than PH patients (p < 0.01. Smokers presenting P. aeruginosa and high frequencies of supragingival plaque were more likely to present CP than PH. P. aeruginosa and Acinetobacter spp. are frequently detected in the oral microbiota of CP. Poor oral hygiene, smoking and the presence of P. aeruginosa are strongly associated with periodontitis.

Antibiotic Sensitivity in Pseudomonas aeruginosa of Diabetic Patient’s Foot Ulcer

OpenAIRE

Pratiwi Apridamayanti; Khairunnisa Azani Meilinasary; Rafika Sari

2016-01-01

Diabetes Mellitus (DM) patients are at risk to have the diabetic ulcer. The main reason for DM’s patient with ulcer complication to be treated and healed in hospital is bacterial infection. One of many bacteria that infects diabetic ulcer is Pseudomonas aeruginosa. This conditian can be treated by antibiotic. The using antibiotic is often inaccurate causing the microbe resistance. To choose the right antibiotic, it needs to test the antibiotic’s sensitivity towards Pseudomonas aeruginosa. The...

Characterization of the Pseudomonas aeruginosa Lol system as a lipoprotein sorting mechanism.

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Tanaka, Shin-Ya; Narita, Shin-Ichiro; Tokuda, Hajime

2007-05-04

Escherichia coli lipoproteins are localized to either the inner or the outer membrane depending on the residue that is present next to the N-terminal acylated Cys. Asp at position 2 causes the retention of lipoproteins in the inner membrane. In contrast, the accompanying study (9) revealed that the residues at positions 3 and 4 determine the membrane specificity of lipoproteins in Pseudomonas aeruginosa. Since the five Lol proteins involved in the sorting of E. coli lipoproteins are conserved in P. aeruginosa, we examined whether or not the Lol proteins of P. aeruginosa are also involved in lipoprotein sorting but utilize different signals. The genes encoding LolCDE, LolA, and LolB homologues were cloned and expressed. The LolCDE homologue thus purified was reconstituted into proteoliposomes with lipoproteins. When incubated in the presence of ATP and a LolA homologue, the reconstituted LolCDE homologue released lipoproteins, leading to the formation of a LolA-lipoprotein complex. Lipoproteins were then incorporated into the outer membrane depending on a LolB homologue. As revealed in vivo, lipoproteins with Lys and Ser at positions 3 and 4, respectively, remained in proteoliposomes. On the other hand, E. coli LolCDE released lipoproteins with this signal and transferred them to LolA of not only E. coli but also P. aeruginosa. These results indicate that Lol proteins are responsible for the sorting of lipoproteins to the outer membrane of P. aeruginosa, as in the case of E. coli, but respond differently to inner membrane retention signals.

The effects of hydrogen peroxide on the circadian rhythms of Microcystis aeruginosa.

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Haifeng Qian

Full Text Available BACKGROUND: The cyanobacterium Microcystis aeruginosa is one of the principal bloom-forming cyanobacteria present in a wide range of freshwater ecosystems. M. aeruginosa produces cyanotoxins, which can harm human and animal health. Many metabolic pathways in M. aeruginosa, including photosynthesis and microcystin synthesis, are controlled by its circadian rhythms. However, whether xenobiotics affect the cyanobacterial circadian system and change its growth, physiology and biochemistry is unknown. We used real-time PCR to study the effect of hydrogen peroxide (H(2O(2 on the expression of clock genes and some circadian genes in M. aeruginosa during the light/dark (LD cycle. RESULTS: The results revealed that H(2O(2 changes the expression patterns of clock genes (kaiA, kaiB, kaiC and sasA and significantly decreases the transcript levels of kaiB, kaiC and sasA. H(2O(2 treatment also decreased the transcription of circadian genes, such as photosynthesis-related genes (psaB, psbD1 and rbcL and microcystin-related genes (mcyA, mcyD and mcyH, and changed their circadian expression patterns. Moreover, the physiological functions of M. aeruginosa, including its growth and microcystin synthesis, were greatly influenced by H(2O(2 treatment during LD. These results indicate that changes in the cyanobacterial circadian system can affect its physiological and metabolic pathways. CONCLUSION: Our findings show that a xenobiotic can change the circadian expression patterns of its clock genes to influence clock-controlled gene regulation, and these influences are evident at the level of cellular physiology.

Positive signature-tagged mutagenesis in Pseudomonas aeruginosa: tracking patho-adaptive mutations promoting airways chronic infection.

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Irene Bianconi

2011-02-01

Full Text Available The opportunistic pathogen Pseudomonas aeruginosa can establish life-long chronic infections in the airways of cystic fibrosis (CF patients. Persistent lifestyle is established with P. aeruginosa patho-adaptive variants, which are clonal with the initially-acquired strains. Several reports indicated that P. aeruginosa adapts by loss-of-function mutations which enhance fitness in CF airways and sustain its clonal expansion during chronic infection. To validate this model of P. aeruginosa adaptation to CF airways and to identify novel genes involved in this microevolution, we designed a novel approach of positive-selection screening by PCR-based signature-tagged mutagenesis (Pos-STM in a murine model of chronic airways infection. A systematic positive-selection scheme using sequential rounds of in vivo screenings for bacterial maintenance, as opposed to elimination, generated a list of genes whose inactivation increased the colonization and persistence in chronic airways infection. The phenotypes associated to these Pos-STM mutations reflect alterations in diverse aspects of P. aeruginosa biology which include lack of swimming and twitching motility, lack of production of the virulence factors such as pyocyanin, biofilm formation, and metabolic functions. In addition, Pos-STM mutants showed altered invasion and stimulation of immune response when tested in human respiratory epithelial cells, indicating that P. aeruginosa is prone to revise the interaction with its host during persistent lifestyle. Finally, sequence analysis of Pos-STM genes in longitudinally P. aeruginosa isolates from CF patients identified signs of patho-adaptive mutations within the genome. This novel Pos-STM approach identified bacterial functions that can have important clinical implications for the persistent lifestyle and disease progression of the airway chronic infection.

Pseudomonas aeruginosa infection alters the macrophage phenotype switching process during wound healing in diabetic mice.

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Chen, Sinuo; Li, Renren; Cheng, Chun; Xu, Jing-Ying; Jin, Caixia; Gao, Furong; Wang, Juan; Zhang, Jieping; Zhang, Jingfa; Wang, Hong; Lu, Lixia; Xu, Guo-Tong; Tian, Haibin

2018-03-07

Macrophages play critical roles in wound healing process. They switch from "classically activated" (M1) phenotype in the early inflammatory phase to "alternatively activated" (M2) phenotype in the later healing phase. However, the dynamic process of macrophage phenotype switching in diabetic wounds burdened with bacteria is unclear. In this report, Pseudomonas aeruginosa, frequently detected in diabetic foot ulcers, was inoculated into cutaneous wounds of db/db diabetic mice to mimic bacterium-infected diabetic wound healing. We observed that P. aeruginosa infection impaired diabetic wound healing and quickly promoted the expression of pro-inflammatory genes (M1 macrophage markers) tumor necrosis factor-α (tnf-α), interleukin-1β (il-1β) and il-6 in wounds. The expression of markers of M2 macrophages, including il-10, arginase-1, and ym1 were also upregulated. In addition, similar gene expression patterns were observed in macrophages isolated directly from wounds. Immunostaining showed that P. aeruginosa infection increased both the ratios of M1 and M2 macrophages in wounds compared with that in control groups, which was further confirmed by in vitro culturing macrophages with P. aeruginosa and skin fibroblast conditioned medium. However, the ratios of the expression levels of pro-inflammatory genes to anti-inflammatory gene il-10 was increased markedly in P. aeruginosa infected wounds and macrophages compared with that in control groups, and P. aeruginosa prolonged the presence of M1 macrophages in the wounds. These data demonstrated that P. aeruginosa in diabetic wounds activates a mixed M1/M2 macrophage phenotype with an excessive activation of M1 phenotype or relatively inadequate activation of M2 phenotype. © 2018 International Federation for Cell Biology.

A multilevel trait-based approach to the ecological performance of Microcystis aeruginosa complex from headwaters to the ocean.

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Kruk, Carla; Segura, Angel M; Nogueira, Lucía; Alcántara, Ignacio; Calliari, Danilo; Martínez de la Escalera, Gabriela; Carballo, Carmela; Cabrera, Carolina; Sarthou, Florencia; Scavone, Paola; Piccini, Claudia

2017-12-01

The Microcystis aeruginosa complex (MAC) clusters cosmopolitan and conspicuous harmful bloom-forming cyanobacteria able to produce cyanotoxins. It is hypothesized that low temperatures and brackish salinities are the main barriers to MAC proliferation. Here, patterns at multiple levels of organization irrespective of taxonomic identity (i.e. a trait-based approach) were analyzed. MAC responses from the intracellular (e.g. respiratory activity) to the ecosystem level (e.g. blooms) were evaluated in wide environmental gradients. Experimental results on buoyancy and respiratory activity in response to increased salinity (0-35) and a literature review of maximum growth rates under different temperatures and salinities were combined with field sampling from headwaters (800km upstream) to the marine end of the Rio de la Plata estuary (Uruguay-South America). Salinity and temperature were the major variables affecting MAC responses. Experimentally, freshwater MAC cells remained active for 24h in brackish waters (salinity=15) while colonies increased their flotation velocity. At the population level, maximum growth rate decreased with salinity and presented a unimodal exponential response with temperature, showing an optimum at 27.5°C and a rapid decrease thereafter. At the community and ecosystem levels, MAC occurred from fresh to marine waters (salinity 30) with a sustained relative increase of large mucilaginous colonies biovolume with respect to individual cells. Similarly, total biomass and, specific and morphological richness decreased with salinity while blooms were only detected in freshwater both at high (33°C) and low (11°C) temperatures. In brackish waters, large mucilaginous colonies presented advantages under osmotic restrictive conditions. These traits values have also been associated with higher toxicity potential. This suggest salinity or low temperatures would not represent effective barriers for the survival and transport of potentially toxic MAC under

The anti-Pseudomonas aeruginosa antibody Panobacumab is efficacious on acute pneumonia in neutropenic mice and has additive effects with meropenem.

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Thomas Secher

Full Text Available Pseudomonas aeruginosa (P. aeruginosa infections are associated with considerable morbidity and mortality in immunocompromised patients due to antibiotic resistance. Therefore, we investigated the efficacy of the anti-P. aeruginosa serotype O11 lipopolysaccharide monoclonal antibody Panobacumab in a clinically relevant murine model of neutropenia induced by cyclophosphamide and in combination with meropenem in susceptible and meropenem resistant P. aeruginosa induced pneumonia. We observed that P. aeruginosa induced pneumonia was dramatically increased in neutropenic mice compared to immunocompetent mice. First, Panobacumab significantly reduced lung inflammation and enhanced bacterial clearance from the lung of neutropenic host. Secondly, combination of Panobacumab and meropenem had an additive effect. Third, Panobacumab retained activity on a meropenem resistant P. aeruginosa strain. In conclusion, the present data established that Panobacumab contributes to the clearance of P. aeruginosa in neutropenic hosts as well as in combination with antibiotics in immunocompetent hosts. This suggests beneficial effects of co-treatment even in immunocompromised individuals, suffering most of the morbidity and mortality of P. aeruginosa infections.

Photoacclimation of cultured strains of the cyanobacterium

NARCIS (Netherlands)

Bañares-España, E.; Kromkamp, J.C.; López-Rodas, V.; Costas, E.; Flores-Moya, A.

2013-01-01

The cyanobacterium Microcystis aeruginosa forms blooms that can consist of colonies. We have investigated how M.aeruginosa acclimatizes to changing light conditions such as can occur during blooms. Three different strains were exposed to two irradiance levels: lower (LL) and higher (HL) than the

Chromosomal organization and segregation in Pseudomonas aeruginosa.

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Isabelle Vallet-Gely

2013-05-01

Full Text Available The study of chromosomal organization and segregation in a handful of bacteria has revealed surprising variety in the mechanisms mediating such fundamental processes. In this study, we further emphasized this diversity by revealing an original organization of the Pseudomonas aeruginosa chromosome. We analyzed the localization of 20 chromosomal markers and several components of the replication machinery in this important opportunistic γ-proteobacteria pathogen. This technique allowed us to show that the 6.3 Mb unique circular chromosome of P. aeruginosa is globally oriented from the old pole of the cell to the division plane/new pole along the oriC-dif axis. The replication machinery is positioned at mid-cell, and the chromosomal loci from oriC to dif are moved sequentially to mid-cell prior to replication. The two chromosomal copies are subsequently segregated at their final subcellular destination in the two halves of the cell. We identified two regions in which markers localize at similar positions, suggesting a bias in the distribution of chromosomal regions in the cell. The first region encompasses 1.4 Mb surrounding oriC, where loci are positioned around the 0.2/0.8 relative cell length upon segregation. The second region contains at least 800 kb surrounding dif, where loci show an extensive colocalization step following replication. We also showed that disrupting the ParABS system is very detrimental in P. aeruginosa. Possible mechanisms responsible for the coordinated chromosomal segregation process and for the presence of large distinctive regions are discussed.

The Versatile Mutational Resistome of Pseudomonas aeruginosa

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Carla López-Causapé

2018-04-01

Full Text Available One of the most striking features of Pseudomonas aeruginosa is its outstanding capacity for developing antimicrobial resistance to nearly all available antipseudomonal agents through the selection of chromosomal mutations, leading to the failure of the treatment of severe hospital-acquired or chronic infections. Recent whole-genome sequencing (WGS data obtained from in vitro assays on the evolution of antibiotic resistance, in vivo monitoring of antimicrobial resistance development, analysis of sequential cystic fibrosis isolates, and characterization of widespread epidemic high-risk clones have provided new insights into the evolutionary dynamics and mechanisms of P. aeruginosa antibiotic resistance, thus motivating this review. Indeed, the analysis of the WGS mutational resistome has proven to be useful for understanding the evolutionary dynamics of classical resistance pathways and to describe new mechanisms for the majority of antipseudomonal classes, including β-lactams, aminoglycosides, fluoroquinolones, or polymixins. Beyond addressing a relevant scientific question, the analysis of the P. aeruginosa mutational resistome is expected to be useful, together with the analysis of the horizontally-acquired resistance determinants, for establishing the antibiotic resistance genotype, which should correlate with the antibiotic resistance phenotype and as such, it should be useful for the design of therapeutic strategies and for monitoring the efficacy of administered antibiotic treatments. However, further experimental research and new bioinformatics tools are still needed to overcome the interpretation limitations imposed by the complex interactions (including those leading to collateral resistance or susceptibility between the 100s of genes involved in the mutational resistome, as well as the frequent difficulties for differentiating relevant mutations from simple natural polymorphisms.

The Versatile Mutational Resistome of Pseudomonas aeruginosa.

Science.gov (United States)

López-Causapé, Carla; Cabot, Gabriel; Del Barrio-Tofiño, Ester; Oliver, Antonio

2018-01-01

One of the most striking features of Pseudomonas aeruginosa is its outstanding capacity for developing antimicrobial resistance to nearly all available antipseudomonal agents through the selection of chromosomal mutations, leading to the failure of the treatment of severe hospital-acquired or chronic infections. Recent whole-genome sequencing (WGS) data obtained from in vitro assays on the evolution of antibiotic resistance, in vivo monitoring of antimicrobial resistance development, analysis of sequential cystic fibrosis isolates, and characterization of widespread epidemic high-risk clones have provided new insights into the evolutionary dynamics and mechanisms of P. aeruginosa antibiotic resistance, thus motivating this review. Indeed, the analysis of the WGS mutational resistome has proven to be useful for understanding the evolutionary dynamics of classical resistance pathways and to describe new mechanisms for the majority of antipseudomonal classes, including β-lactams, aminoglycosides, fluoroquinolones, or polymixins. Beyond addressing a relevant scientific question, the analysis of the P. aeruginosa mutational resistome is expected to be useful, together with the analysis of the horizontally-acquired resistance determinants, for establishing the antibiotic resistance genotype, which should correlate with the antibiotic resistance phenotype and as such, it should be useful for the design of therapeutic strategies and for monitoring the efficacy of administered antibiotic treatments. However, further experimental research and new bioinformatics tools are still needed to overcome the interpretation limitations imposed by the complex interactions (including those leading to collateral resistance or susceptibility) between the 100s of genes involved in the mutational resistome, as well as the frequent difficulties for differentiating relevant mutations from simple natural polymorphisms.

Draft Genome Sequences of Pseudomonas aeruginosa B3 Strains Isolated from a Cystic Fibrosis Patient Undergoing Antibiotic Chemotherapy

DEFF Research Database (Denmark)

Marvig, Rasmus Lykke; Jochumsen, Nicholas; Johansen, Helle Krogh

2013-01-01

Pseudomonas aeruginosa frequently establishes chronic infections in the airways of patients suffering from cystic fibrosis (CF). Here, we report the draft genome sequences of four P. aeruginosa B3 strains isolated from a chronically infected CF patient undergoing antibiotic chemotherapy.......Pseudomonas aeruginosa frequently establishes chronic infections in the airways of patients suffering from cystic fibrosis (CF). Here, we report the draft genome sequences of four P. aeruginosa B3 strains isolated from a chronically infected CF patient undergoing antibiotic chemotherapy....

Activity of Bacteriophages in Removing Biofilms of Pseudomonas aeruginosa Isolates from Chronic Rhinosinusitis Patients

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Stephanie A. Fong

2017-09-01

Full Text Available Introduction:Pseudomonas aeruginosa infections are prevalent amongst chronic rhinosinusitis (CRS sufferers. Many P. aeruginosa strains form biofilms, leading to treatment failure. Lytic bacteriophages (phages are viruses that infect, replicate within, and lyse bacteria, causing bacterial death.Aim: To assess the activity of a phage cocktail in eradicating biofilms of ex vivo P.aeruginosa isolates from CRS patients.Methods: P. aeruginosa isolates from CRS patients with and without cystic fibrosis (CF across three continents were multi-locus sequence typed and tested for antibiotic resistance. Biofilms grown in vitro were treated with a cocktail of four phages (CT-PA. Biofilm biomass was measured after 24 and 48 h, using a crystal violet assay. Phage titrations were performed to confirm replication of the phages. A linear mixed effects model was applied to assess the effects of treatment, time, CF status, and multidrug resistance on the biomass of the biofilm.Results: The isolates included 44 strain types. CT-PA treatment significantly reduced biofilm biomass at both 24 and 48 h post-treatment (p < 0.0001, regardless of CF status or antibiotic resistance. Biomass was decreased by a median of 76% at 48 h. Decrease in biofilm was accompanied by a rise in phage titres for all except one strain.Conclusion: A single dose of phages is able to significantly reduce biofilms formed in vitro by a range of P.aeruginosa isolates from CRS patients. This represents an exciting potential and novel targeted treatment for P. aeruginosa biofilm infections and multidrug resistant bacteria.

Phenotypic characterization and colistin susceptibilities of carbapenem-resistant of Pseudomonas aeruginosa and Acinetobacter spp.

Science.gov (United States)

Mohanty, Srujana; Maurya, Vijeta; Gaind, Rajni; Deb, Monorama

2013-11-15

Pseudomonas aeruginosa and Acinetobcter spp. are important nosocomial pathogens and carbapenem resistance is an emerging threat. Therapeutic options for infections with these isolates include colistin. This study was conducted to determine the prevalence of carbapenem resistance in P. aeruginosa and Acinetobacter spp. bloodstream isolates, phenotypically characterize the resistance mechanisms and evaluate the in vitro activity of colistin. Consecutive 145 (95 P.aeruginosa and 50 Acinetobacter spp.) non-repeat isolates were included. Antibiotic susceptibility testing was performed per CLSI guidelines. MIC for carbapenems and colistin was performed using Etest. Isolates showing reduced susceptibility or resistance to the carbapenems were tested for metallo-β-lactamase (MBL) production using imipenem-EDTA combined disk and MBL Etest. Carbapenem resistance was observed in 40% P. aeruginosa and 66.0% Acinetobacter spp. Carbapenem-resistant (CA-R) isolates were significantly (p carbapenem-susceptible isolates. Approximately half of the CA-R strains were multidrug-resistant, and 3.1-5.5% were resistant to all antibiotics tested. MBL was found in 76.3% and 69.7% of the P. aeruginosa and Acinetobacter spp., respectively. Colistin resistance was observed in three (6.0%) Acinetobacter isolates and eight (8.4%) P. aeruginosa. MIC50 for carbapenems were two to four times higher for MBL-positive compared to MBL-negative isolates, but no difference was seen in MIC for colistin. Carbapenem resistance was observed to be mediated by MBL in a considerable number of isolates. Colistin is an alternative for infections caused by CA-R isolates; however, MIC testing should be performed whenever clinical use of colistin is considered.

Varroa-Virus Interaction in Collapsing Honey Bee Colonies

DEFF Research Database (Denmark)

Francis, Roy Mathew; Nielsen, Steen L.; Kryger, Per

2013-01-01

Varroa mites and viruses are the currently the high-profile suspects in collapsing bee colonies. Therefore, seasonal variation in varroa load and viruses (Acute-Kashmir-Israeli complex (AKI) and Deformed Wing Virus (DWV)) were monitored in a year-long study. We investigated the viral titres...... in honey bees and varroa mites from 23 colonies (15 apiaries) under three treatment conditions: Organic acids (11 colonies), pyrethroid (9 colonies) and untreated (3 colonies). Approximately 200 bees were sampled every month from April 2011 to October 2011, and April 2012. The 200 bees were split to 10...... subsamples of 20 bees and analysed separately, which allows us to determine the prevalence of virus-infected bees. The treatment efficacy was often low for both treatments. In colonies where varroa treatment reduced the mite load, colonies overwintered successfully, allowing the mites and viruses...

Pseudomonas aeruginosa. Vacunas: un reto a la investigación

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Sara C. Esnard

2004-04-01

Full Text Available Pseudomonas aeruginosa, patógeno gramnegativo versátil y oportunista debido a su gran adaptabilidad fisiológica, potencial metabólico y mecanismos de virulencia, es causa frecuente a escala mundial de severas o letales infecciones en pacientes hospitalizados. El empeño por lograr terapias alternativas para prevenir o combatir las infecciones producidas por P. aeruginosa ha ocupado a investigadores de todo el mundo desde la segunda mitad del pasado siglo y actualmente se continúan reportando trabajos que respaldan los ensayos de candidatos vacunales, fundamentalmente a partir de antígenos proteicos, mayoritariamente basados en la construcción de vacunas recombinantes. En este artículo se presenta una revisión de trabajos publicados sobre las investigaciones desarrolladas en diferentes países, con el objetivo de obtener candidatos vacunales para la prevención o tratamiento de las infecciones causadas por Pseudomonas aeruginosa, a partir de la década de los años 50 del siglo XX hasta el 2003.

Rapid identification of Pseudomonas aeruginosa by pulsed-field gel electrophoresis.

Science.gov (United States)

Selim, Samy; El Kholy, Iman; Hagagy, Nashwa; El Alfay, Sahar; Aziz, Mohamed Abdel

2015-01-02

Twenty clinical Pseudomonas aeruginosa isolates recovered from patients admitted to The General Hospital in Ismailia Governorate (Egypt) were examined in this study. We analysed P. aeruginosa ATCC 9027 (as a control strain) and 19 of the isolates after digestion with SpeI restriction endonuclease. After this we conducted a pulsed-field gel electrophoresis (PFGE) and typed the obtained 10 unique patterns, designated as A, A1, B, B1, C, C1, D, D1, E and F. We evaluated the genetic relatedness between all strains, based on ≥87% band identity. As a result, the isolates were grouped in the 10 clusters as follows: patterns A, A1, B, B1, C contained two strains each and patterns C1, D, D1, E contained a single strain each; the five remaining strains were closely related (genomic pattern F). One isolate belonged to antibiotype 'b'. The genotype patterns of the P. aeruginosa ATCC 9027 control strain and isolate no. 11 were closely related and had two different antibiotypes 'd' and 'c', respectively.

Trehalose biosynthesis promotes Pseudomonas aeruginosa pathogenicity in plants.

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Djonović, Slavica; Urbach, Jonathan M; Drenkard, Eliana; Bush, Jenifer; Feinbaum, Rhonda; Ausubel, Jonathan L; Traficante, David; Risech, Martina; Kocks, Christine; Fischbach, Michael A; Priebe, Gregory P; Ausubel, Frederick M

2013-03-01

Pseudomonas aeruginosa strain PA14 is a multi-host pathogen that infects plants, nematodes, insects, and vertebrates. Many PA14 factors are required for virulence in more than one of these hosts. Noting that plants have a fundamentally different cellular architecture from animals, we sought to identify PA14 factors that are specifically required for plant pathogenesis. We show that synthesis by PA14 of the disaccharide trehalose is required for pathogenesis in Arabidopsis, but not in nematodes, insects, or mice. In-frame deletion of two closely-linked predicted trehalose biosynthetic operons, treYZ and treS, decreased growth in Arabidopsis leaves about 50 fold. Exogenously co-inoculated trehalose, ammonium, or nitrate, but not glucose, sulfate, or phosphate suppressed the phenotype of the double ΔtreYZΔtreS mutant. Exogenous trehalose or ammonium nitrate does not suppress the growth defect of the double ΔtreYZΔtreS mutant by suppressing the plant defense response. Trehalose also does not function intracellularly in P. aeruginosa to ameliorate a variety of stresses, but most likely functions extracellularly, because wild-type PA14 rescued the in vivo growth defect of the ΔtreYZΔtreS in trans. Surprisingly, the growth defect of the double ΔtreYZΔtreS double mutant was suppressed by various Arabidopsis cell wall mutants that affect xyloglucan synthesis, including an xxt1xxt2 double mutant that completely lacks xyloglucan, even though xyloglucan mutants are not more susceptible to pathogens and respond like wild-type plants to immune elicitors. An explanation of our data is that trehalose functions to promote the acquisition of nitrogen-containing nutrients in a process that involves the xyloglucan component of the plant cell wall, thereby allowing P. aeruginosa to replicate in the intercellular spaces in a leaf. This work shows how P. aeruginosa, a multi-host opportunistic pathogen, has repurposed a highly conserved "house-keeping" anabolic pathway (trehalose

Trehalose biosynthesis promotes Pseudomonas aeruginosa pathogenicity in plants.

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Slavica Djonović

2013-03-01

Full Text Available Pseudomonas aeruginosa strain PA14 is a multi-host pathogen that infects plants, nematodes, insects, and vertebrates. Many PA14 factors are required for virulence in more than one of these hosts. Noting that plants have a fundamentally different cellular architecture from animals, we sought to identify PA14 factors that are specifically required for plant pathogenesis. We show that synthesis by PA14 of the disaccharide trehalose is required for pathogenesis in Arabidopsis, but not in nematodes, insects, or mice. In-frame deletion of two closely-linked predicted trehalose biosynthetic operons, treYZ and treS, decreased growth in Arabidopsis leaves about 50 fold. Exogenously co-inoculated trehalose, ammonium, or nitrate, but not glucose, sulfate, or phosphate suppressed the phenotype of the double ΔtreYZΔtreS mutant. Exogenous trehalose or ammonium nitrate does not suppress the growth defect of the double ΔtreYZΔtreS mutant by suppressing the plant defense response. Trehalose also does not function intracellularly in P. aeruginosa to ameliorate a variety of stresses, but most likely functions extracellularly, because wild-type PA14 rescued the in vivo growth defect of the ΔtreYZΔtreS in trans. Surprisingly, the growth defect of the double ΔtreYZΔtreS double mutant was suppressed by various Arabidopsis cell wall mutants that affect xyloglucan synthesis, including an xxt1xxt2 double mutant that completely lacks xyloglucan, even though xyloglucan mutants are not more susceptible to pathogens and respond like wild-type plants to immune elicitors. An explanation of our data is that trehalose functions to promote the acquisition of nitrogen-containing nutrients in a process that involves the xyloglucan component of the plant cell wall, thereby allowing P. aeruginosa to replicate in the intercellular spaces in a leaf. This work shows how P. aeruginosa, a multi-host opportunistic pathogen, has repurposed a highly conserved "house-keeping" anabolic

Novel targets of the CbrAB/Crc carbon catabolite control system revealed by transcript abundance in Pseudomonas aeruginosa.