Blar i forfatter "Sivertsen, Audun"

Viser treff 1-7 av 7

    • Alternative vanHAX promoters and increased vanA-plasmid copy number resurrect silenced glycopeptide resistance in Enterococcus faecium 

      Wagner, Theresa; Janice, Jessin; Sivertsen, Audun; Sjögren, Ingegerd; Sundsfjord, Arnfinn; Hegstad, Kristin (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-12-26)
      <i>Background</i> - Vancomycin variable enterococci (VVE) are <i>van</i>-positive isolates with a susceptible phenotype that can convert to a resistant phenotype during vancomycin selection.<p> <p><i>Objectives</i> - To describe a vancomycin-susceptible <i>vanA</i>-PCR positive ST203 VVE <i>Enterococcus faecium</i> isolate (VVE<i>Swe</i>-S) from a liver transplantation patient in Sweden which ...

    • The enterococcus cassette chromosome, a genomic variation enabler in enterococci 

      Sivertsen, Audun; James Peter, Jessin Janice; Pedersen, Torunn Annie; Wagner, Theresa; Hegstad, Joachim; Hegstad, Kristin (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-11-07)
      Enterococcus faecium has a highly variable genome prone to recombination and horizontal gene transfer. Here, we have identified a novel genetic island with an insertion locus and mobilization genes similar to those of staphylococcus cassette chromosome elements SCCmec. This novel element termed the enterococcus cassette chromosome (ECC) element was located in the 3′ region of rlmH and encoded large ...

    • Mobile genetic elements causing plasticity in E. faecium 

      Sivertsen, Audun (Doctoral thesis; Doktorgradsavhandling, 2017-03-24)
      I helseinstitusjoner vancomycin-resistente enterokokker en fryktet bakterie som kan lage alvorlig infeksjonssykdom i pasienter med dårlig immunforsvar, og er vanskelig å behandle. Avhandlingen fokuserer på vancomycin-resistente enterokokker (VRE), og hvordan disse bakteriene gjennom å overføre gener mellom hverandre kan utvikle resistens mot antibiotika. Vi har analysert to utbrudd av VRE i Sverige ...

    • A multicentre hospital outbreak in Sweden caused by introduction of a vanB2 transposon into a stably maintained pRUM-plasmid in an Enterococcus faecium ST192 clone. 

      Sivertsen, Audun; Billström, Hanna; Melefors, Öjar; Liljequist, Barbro Olsson; Wisell, Karin Tegmark; Ullberg, Måns; Özenci, Volkan; Sundsfjord, Arnfinn; Hegstad, Kristin (Journal article; Tidsskriftartikkel; Peer reviewed, 2014)
      The clonal dissemination of VanB-type vancomycin-resistant Enterococcus faecium (VREfm) strains in three Swedish hospitals between 2007 and 2011 prompted further analysis to reveal the possible origin and molecular characteristics of the outbreak strain. A representative subset of VREfm isolates (n = 18) and vancomycin-susceptible E. faecium (VSEfm, n = 2) reflecting the spread in time and location ...

    • Possible origin of a vanB-type Enterococcus faecium causing a multicentre outbreak in Sweden 

      Sivertsen, Audun (Master thesis; Mastergradsoppgave, 2013-11-01)
      Dissemination of vancomycin-resistant Enterococcus faecium (VREfm) with similar pulsed-field gel electrophoresis patterns in three Swedish hospitals between 2007 and 2011 prompted molecular characterization to reveal the possible origins and features of the strain. A representative subset of collected isolates (VREfm (n=18) and vancomycin-susceptible Enterococcus faecium (VSEfm) (n=2)) reflecting ...

    • Role of Horizontal Gene Transfer in the Development of Multidrug Resistance in Haemophilus influenzae 

      Hegstad, Kristin; Mylvaganam, Haima; Janice, Jessin; Josefsen, Ellen H.; Sivertsen, Audun; Skaare, Dagfinn (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-01-29)
      <i>Haemophilus influenzae</i> colonizes the respiratory tract in humans and causes both invasive and noninvasive infections. Resistance to extended-spectrum cephalosporins in <i>H. influenzae</i> is rare in Europe. In this study, we defined acquired resistance gene loci and <i>ftsI</i> mutations in multidrug-resistant (MDR) and/or PBP3-mediated beta-lactam-resistant (rPBP3) <i>H. influenzae</i> ...

    • Silenced vanA gene cluster on a transferable plasmid cause outbreak of vancomycin variable enterococci 

      Sivertsen, Audun; Pedersen, Torunn Annie; Larssen, Kjersti Wik; Bergh, Kåre; Rønning, Torunn Gresdal; Radtke, Andreas; Hegstad, Kristin (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-05-02)
      We report an outbreak of vancomycin-variable vanA+ enterococci (VVE) able to escape phenotypic detection by current guide- lines and demonstrate the molecular mechanisms for in vivo switching into vancomycin resistance and horizontal spread of the vanA cluster. Forty-eight vanA+ Enterococcus faecium isolates and one Enterococcus faecalis isolate were analyzed for clonality with pulsed-field ...