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  • 1
    Language: English
    In: Microbes and Infection, April, 2012, Vol.14(4), p.329(6)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.micinf.2011.10.008 Byline: Manfred Rohde (b), Susanne R. Talay (b), Magnus Rasmussen (a) Abstract: Streptococcus dysgalactiae subsp. equisimilis (SDSE) can cause recurrent bacteremic infection. We have characterized novel virulence properties of an SDSE isolate of type stG485.0 that caused severe sepsis three times in a patient despite that he had opsonizing antibodies to the isolate. An infected aortic aneurysm was suspected to be the focus for the persisting bacteria. For the first time we show that this SDSE isolate, as well as other invasive SDSE isolates, aggregate human platelets and efficiently internalize into human endothelial cells. These properties may aid SDSE to persist and could explain the tendency of SDSE to cause recurrent bacteremia. Author Affiliation: (a) Division of Infection Medicine, Department of Clinical Sciences, Lund University, BMC B14, Tornavagen 10, 221 84 Lund, Sweden (b) Department of Medical Microbiology, Helmholtz Centre for Infection Research, Braunschweig, Germany Article History: Received 28 February 2011; Accepted 24 October 2011
    Keywords: Aneurysm
    ISSN: 1286-4579
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  • 2
    Language: English
    In: PLoS ONE, 01 January 2014, Vol.9(1), p.e86935
    Description: The clinical relevance of nosocomially acquired infections caused by multi-resistant Achromobacter strains is rapidly increasing. Here, a diverse set of 61 Achromobacter xylosoxidans strains was characterized by MultiLocus Sequence Typing and Phenotype MicroArray technology. The strains were further analyzed in regard to their susceptibility to 35 antibiotics and to 34 different and newly isolated bacteriophages from the environment. A large proportion of strains were resistant against numerous antibiotics such as cephalosporines, aminoglycosides and quinolones, whereas piperacillin-tazobactam, ticarcillin, mezlocillin and imipenem were still inhibitory. We also present the first expanded study on bacteriophages of the genus Achromobacter that has been so far a blank slate with respect to phage research. The phages were isolated mainly from several waste water treatment plants in Germany. Morphological analysis of all of these phages by electron microscopy revealed a broad diversity with different members of the order Caudovirales, including the families Siphoviridae, Myoviridae, and Podoviridae. A broad spectrum of different host ranges could be determined for several phages that lysed up to 24 different and in part highly antibiotic resistant strains. Molecular characterisation by DNA restriction analysis revealed that all phages contain linear double-stranded DNA. Their restriction patterns display distinct differences underlining their broad diversity.
    Keywords: Sciences (General)
    E-ISSN: 1932-6203
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  • 3
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 2010, Vol.107(19), pp.8748-8753
    Description: Balanced induction of proinflammatory and type I IFN responses upon activation of Toll-like receptors (TLRs) determines the outcome of microbial infections and the pathogenesis of autoimmune and other inflammatory diseases. Mast cells, key components of the innate immune system, are known for their debilitating role in allergy and autoimmunity. However, their role in antimicrobial host defenses is being acknowledged increasingly. How mast cells interact with microbes and the nature of responses triggered thereby is not well characterized. Here we show that in response to TLR activation by Gram-positive and -negative bacteria or their components, mast cells elicit proinflammatory but not type I IFN responses. We demonstrate that in mast cells, bound bacteria and TLR ligands remain trapped at the cell surface and do not undergo internalization, a prerequisite for type I IFN induction. Such cells, however, can elicit type I IFNs in response to vesicular stomatitis virus which accesses the cytosolic retinoic acid-inducible gene I receptor. Although important for antiviral immunity, a strong I IFN response is known to contribute to pathogenesis of several bacterial pathogens such as Listeria monocytogenes. Interestingly, we observed that the mast cell-dependent neutrophil mobilization upon L. monocytogenes infection is highly impaired by IFN-β. Thus, the fact that mast cells, although endowed with the capacity to elicit type I IFNs in response to viral infection, elicit only proinflammatory responses upon bacterial infection shows that mast cells, key effector cells of the innate immune system, are well adjusted for optimal antibacterial and antiviral responses. ; Includes references ; p. 8748-8753.
    Keywords: Biological Response Modifiers -- Properties ; Autoimmunity -- Research ; Interferon -- Dosage And Administration ; Antibacterial Agents -- Dosage And Administration ; Bacterial Infections -- Drug Therapy ; Lysosomes -- Properties ; Stomatitis -- Drug Therapy ; Mast Cells -- Properties;
    ISSN: 0027-8424
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  • 4
    In: Molecular Microbiology, September 2011, Vol.81(6), pp.1577-1592
    Description: accumulates large amounts of triacylglycerol (TAG) which acts as storage compounds for energy and carbon. The mycobacterial triacylglycerols stored in the form of intracellular lipid droplets are essential for long‐term survival of during a dormant state. We report here that when the mycolytransferase Ag85A is overexpressed in mc155, cell morphology was changed and the cells became grossly enlarged. A massive formation of lipid bodies and a change in lipid pattern was observed simultaneously. We suspected a possible role of Ag85A in the acyl lipid metabolism and discovered that the enzyme possesses acyl‐CoA:diacylglycerol acyltransferase (DGAT) activity in addition to its well‐known function as mycolyltransferase. Ag85A mediates the transesterification of diacylglycerol using long‐chain acyl‐CoA as acyl donors. The and values for palmitoleoyl‐coenzyme A were 390 µM and 55.54 min respectively. A docking model suggests that palmitoleoyl‐coenzyme A and 1,2‐dipalmitin occupy the same active site as trehalose 6,6′‐dimycolate and trehalose 6′‐monomycolate. The site‐directed Ser126Ala mutation of the active site proved that this residue is involved in the catalytic activity of this enzyme. Although not proven conclusively for dormant stage of , our novel finding about the synthesis of TAGs by Ag85A strongly suggests that Ag85A may play a significant role in the formation of lipid storage bodies and thus also in the establishment and maintenance of a persistent tuberculosis infection.
    Keywords: Medical Law -- Physiological Aspects ; Medical Law -- Analysis ; Tuberculosis -- Physiological Aspects ; Tuberculosis -- Analysis ; Enzymes -- Physiological Aspects ; Enzymes -- Analysis ; Triglycerides -- Physiological Aspects ; Triglycerides -- Analysis;
    ISSN: 0950-382X
    E-ISSN: 1365-2958
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  • 5
    Language: English
    In: Applied and environmental microbiology, 15 August 2015, Vol.81(16), pp.5411-9
    Description: Paenibacillus larvae is the causative agent of American foulbrood (AFB), the most serious honey bee brood bacterial disease. We isolated and characterized P. larvae-directed bacteriophages and developed criteria for safe phage therapy. Whole-genome analysis of a highly lytic virus of the family Siphoviridae (HB10c2) provided a detailed safety profile and uncovered its lysogenic nature and a putative beta-lactamase-like protein. To rate its antagonistic activity against the pathogens targeted and to specify potentially harmful effects on the bee population and the environment, P. larvae genotypes ERIC I to IV, representatives of the bee gut microbiota, and a broad panel of members of the order Bacillales were analyzed for phage HB10c2-induced lysis. Breeding assays with infected bee larvae revealed that the in vitro phage activity observed was not predictive of the real-life scenario and therapeutic efficacy. On the basis of the disclosed P. larvae-bacteriophage coevolution, we discuss the future prospects of AFB phage therapy.
    Keywords: Bacteriophages -- Growth & Development ; Bees -- Microbiology ; Paenibacillus -- Virology
    ISSN: 00992240
    E-ISSN: 1098-5336
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  • 6
    Language: English
    In: BMC Microbiology, May 14, 2011, Vol.11, p.102
    Description: Background Phages could be an important alternative to antibiotics, especially for treatment of multiresistant bacteria as e.g. Pseudomonas aeruginosa. For an effective use of bacteriophages as antimicrobial agents, it is important to understand phage biology but also genes of the bacterial host essential for phage infection. Results We isolated and characterized a lytic Pseudomonas aeruginosa phage, named JG004, and sequenced its genome. Phage JG004 is a lipopolysaccharide specific broad-host-range phage of the Myoviridae phage family. The genome of phage JG004 encodes twelve tRNAs and is highly related to the PAK-P1 phage genome. To investigate phage biology and phage-host interactions, we used transposon mutagenesis of the P. aeruginosa host and identified P. aeruginosa genes, which are essential for phage infection. Analysis of the respective P. aeruginosa mutants revealed several characteristics, such as host receptor and possible spermidine-dependance of phage JG004. Conclusions Whole genome sequencing of phage JG004 in combination with identification of P. aeruginosa host genes essential for infection, allowed insights into JG004 biology, revealed possible resistance mechanisms of the host bacterium such as mutations in LPS and spermidine biosynthesis and can also be used to characterize unknown gene products in P. aeruginosa.
    Keywords: Genomes -- Physiological Aspects ; Genomes -- Research ; Bacteriophages -- Genetic Aspects ; Bacteriophages -- Research ; Dna Sequencing -- Usage
    ISSN: 1471-2180
    Source: Cengage Learning, Inc.
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  • 7
    Language: English
    In: BMC Microbiology, May 14, 2011, Vol.11, p.102
    Description: Background Phages could be an important alternative to antibiotics, especially for treatment of multiresistant bacteria as e.g. Pseudomonas aeruginosa. For an effective use of bacteriophages as antimicrobial agents, it is important to understand phage biology but also genes of the bacterial host essential for phage infection. Results We isolated and characterized a lytic Pseudomonas aeruginosa phage, named JG004, and sequenced its genome. Phage JG004 is a lipopolysaccharide specific broad-host-range phage of the Myoviridae phage family. The genome of phage JG004 encodes twelve tRNAs and is highly related to the PAK-P1 phage genome. To investigate phage biology and phage-host interactions, we used transposon mutagenesis of the P. aeruginosa host and identified P. aeruginosa genes, which are essential for phage infection. Analysis of the respective P. aeruginosa mutants revealed several characteristics, such as host receptor and possible spermidine-dependance of phage JG004. Conclusions Whole genome sequencing of phage JG004 in combination with identification of P. aeruginosa host genes essential for infection, allowed insights into JG004 biology, revealed possible resistance mechanisms of the host bacterium such as mutations in LPS and spermidine biosynthesis and can also be used to characterize unknown gene products in P. aeruginosa.
    Keywords: Genomes -- Physiological Aspects ; Genomes -- Research ; Bacteriophages -- Genetic Aspects ; Bacteriophages -- Research ; Dna Sequencing -- Usage
    ISSN: 1471-2180
    Source: Cengage Learning, Inc.
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  • 8
    Language: English
    In: Infection and Immunity, 2011, Vol. 79(1), p.44
    Description: The genomic analysis of Streptococcus pneumoniae predicted six putative glutamine uptake systems, which are expressed under in vitro conditions, as shown here by reverse transcription-PCR. Four of these operons consist of glnHPQ, while two lack glnH, which encodes a soluble glutamine-binding protein. Here, we studied the impact of two of these glutamine ATP-binding cassette transporters on S. pneumoniae D39 virulence and phagocytosis, which consist of GlnQ and a translationally fused protein of GlnH and GlnP. Mice infected intranasally with D39 Delta gln0411/0412 showed significantly increased survival times and a significant delay in the development of pneumococcal pneumonia compared to those infected with D39, as observed in real time using bioluminescent pneumococci. In a mouse sepsis model, the mutant D39 Delta gln0411/0412 showed only moderate but significant attenuation. In contrast, the D39 Delta gln1098/1099 knockout strain was massively attenuated in the pneumonia and septicemia mouse infection model. To cause pneumonia or sepsis with D39 Delta gln1098/1099, infection doses 100- to 10,000-fold higher than those used for wild-type strain D39 were required. In an experimental mouse meningitis model, D39 Delta gln1098/1099 produced decreased levels of white blood cells in cerebrospinal fluid and showed decreased numbers of bacteria in the bloodstream compared to D39 and D39 Delta gln0411/0412. Phagocytosis experiments revealed significantly decreased intracellular survival rates of mutants D39 Delta gln1098/1099 and D39 Delta gln0411/0412 compared to wild-type D39, suggesting that the deficiency of Gln uptake systems impairs resistance to oxidative stress. Taken together, our results demonstrate that both glutamine uptake systems are required for full virulence of pneumococci but exhibit different impacts on the pathogenesis of pneumococci under in vivo conditions.
    Keywords: Fitness ; Translation ; Glutamine ; Septicemia ; Leukocytes ; Animal Models ; Survival ; Infection ; Meningitis ; Virulence ; Sepsis ; Cerebrospinal Fluid ; Oxidative Stress ; ATP-Binding Protein ; Genomic Analysis ; Fused Protein ; Operons ; Phagocytosis ; Pneumonia ; Streptococcus Pneumoniae ; Microorganisms & Parasites ; Animal Diseases;
    ISSN: 0019-9567
    ISSN: 00199567
    E-ISSN: 10985522
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  • 9
    Language: English
    In: PLoS ONE, 2012, Vol.7(5), p.e37416
    Description: Pretubulysin is a natural product that is found in strains of myxobacteria in only minute amounts. It represents the first enzyme-free intermediate in the biosynthesis of tubulysins and undergoes post-assembly acylation and oxidation reactions. Pretubulysin inhibits the growth of cultured mammalian cells, as do tubulysins, which are already in advanced preclinical development as anticancer and antiangiogenic agents. The mechanism of action of this highly potent compound class involves the depolymerization of microtubules, thereby inducing mitotic arrest. Supply issues with naturally occurring derivatives can now be circumvented by the total synthesis of pretubulysin, which, in contrast to tubulysin, is synthetically accessible in gram-scale quantities. We show that the simplified precursor is nearly equally potent to the parent compound. Pretubulysin induces apoptosis and inhibits cancer cell migration and tubulin assembly in vitro. Consequently, pretubulysin appears to be an ideal candidate for future development in preclinical trials and is a very promising early lead structure in cancer therapy.
    Keywords: Research Article ; Biology ; Chemistry ; Medicine ; Chemistry ; Molecular Biology ; Cell Biology ; Oncology ; Biochemistry
    E-ISSN: 1932-6203
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  • 10
    Language: English
    In: PLoS ONE, 2011, Vol.6(5), p.e20075
    Description: The delta subunit of the RNA polymerase, RpoE, maintains the transcriptional specificity in Gram-positive bacteria. Lack of RpoE results in massive changes in the transcriptome of the human dental caries pathogen Streptococcus mutans . In this study, we analyzed traits of the Δ rpoE mutant which are important for biofilm formation and interaction with oral microorganisms and human cells and performed a global phenotypic analysis of its physiological functions. The Δ rpoE mutant showed higher self-aggregation compared to the wild type and coaggregated with other oral bacteria and Candida albicans . It formed a biofilm with a different matrix structure and an altered surface attachment. The amount of the cell surface antigens I/II SpaP and the glucosyltransferase GtfB was reduced. The Δ rpoE mutant displayed significantly stronger adhesion to human extracellular matrix components, especially to fibronectin, than the wild type. Its adhesion to human epithelial cells HEp-2 was reduced, probably due to the highly aggregated cell mass. The analysis of 1248 physiological traits using phenotype microarrays showed that the Δ rpoE mutant metabolized a wider spectrum of carbon sources than the wild type and had acquired resistance to antibiotics and inhibitory compounds with various modes of action. The reduced antigenicity, increased aggregation, adherence to fibronection, broader substrate spectrum and increased resistance to antibiotics of the Δ rpoE mutant reveal the physiological potential of S. mutans and show that some of its virulence related traits are increased.
    Keywords: Research Article ; Biology ; Microbiology
    E-ISSN: 1932-6203
    Source: PLoS
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