• Conserved collateral antibiotic susceptibility networks in diverse clinical strains of Escherichia coli 

      Podnecky, Nicole L.; Aarag, Elizabeth; Kloos, Julia Maria; Sørum, Vidar; Primicerio, Raul; Roberts, Adam Paul; Rozen, Daniel E.; Samuelsen, Ørjan; Johnsen, Pål Jarle (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-09-10)
      There is urgent need to develop novel treatment strategies to reduce antimicrobial resistance. Collateral sensitivity (CS), where resistance to one antimicrobial increases susceptibility to other drugs, might enable selection against resistance during treatment. However, the success of this approach would depend on the conservation of CS networks across genetically diverse bacterial strains. Here, ...
    • Costs and benefits of natural transformation in Acinetobacter baylyi 

      Hülter, Nils Fredrik; Sørum, Vidar; Borch-Pedersen, Kristina; Liljegren, Mikkel Meyn; Utnes, Ane; Primicerio, Raul; Harms, Klaus; Johnsen, Pål Jarle (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-02-15)
      Background <br> Natural transformation enables acquisition of adaptive traits and drives genome evolution in prokaryotes. Yet, the selective forces responsible for the evolution and maintenance of natural transformation remain elusive since taken-up DNA has also been hypothesized to provide benefits such as nutrients or templates for DNA repair to individual cells. <br> Results <br> We investigated ...
    • Evolution of β-lactamase-mediated cefiderocol resistance 

      Frøhlich, Christopher; Sørum, Vidar; Tokuriki, Nobuhiko; Johnsen, Pål Jarle; Samuelsen, Ørjan (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-07-11)
      Background: Cefiderocol is a novel siderophore β-lactam with improved hydrolytic stability toward β-lactamases, including carbapenemases, achieved by combining structural moieties of two clinically efficient cephalosporins, ceftazidime and cefepime. Consequently, cefiderocol represents a treatment alternative for infections caused by MDR Gram-negatives.<p> <p>Objectives: To study the role of ...
    • Evolutionary Instability of Collateral Susceptibility Networks in Ciprofloxacin-Resistant Clinical Escherichia coli Strains 

      Sørum, Vidar; Øynes, Emma Lu; Sollied Møller, Anna; Harms, Klaus; Samuelsen, Ørjan; Podnecky, Nicole L.; Johnsen, Pål Jarle (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-07-07)
      ABSTRACT Collateral sensitivity and resistance occur when resistance development toward one antimicrobial either potentiates or deteriorates the effect of others. Previous reports on collateral effects on susceptibility focus on newly acquired resistance determinants and propose that novel treatment guidelines informed by collateral networks may reduce the evolution, selection, and spread of ...
    • Genetic dominance governs the evolution and spread of mobile genetic elements in bacteria 

      Rodríguez-Beltrán, Jerónimo; Sørum, Vidar; Toll-Riera, Macarena; de la Vega, Carmen; Peña-Miller, Rafael; San Millán, Álvaro (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-22)
      Mobile genetic elements (MGEs), such as plasmids, promote bacterial evolution through horizontal gene transfer (HGT). However, the rules governing the repertoire of traits encoded on MGEs remain unclear. In this study, we uncovered the central role of genetic dominance shaping genetic cargo in MGEs, using antibiotic resistance as a model system. MGEs are typically present in more than one copy per ...
    • OXA-48-Mediated Ceftazidime-Avibactam Resistance Is Associated with Evolutionary Trade-Offs 

      Fröhlich, Christopher; Sørum, Vidar; Thomassen, Ane Molden; Johnsen, Pål Jarle; Samuelsen, Ørjan (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-03-27)
      Infections due to carbapenemase-producing Gram-negative pathogens are associated with limited treatment options and consequently lead to increased mortality and morbidity. In response, combinations of existing β-lactams and novel β-lactamase inhibitors, such as ceftazidime-avibactam (CAZ-AVI), have been developed as alternative treatment options. To understand the development of resistance and ...
    • Spawning behaviour of Arctic charr (Salvelinus alpinus) : risk of sperm competition and timing of milt release for sneaker and dominant males 

      Sørum, Vidar; Figenschou, Lars; Rudolfsen, Geir; Folstad, Ivar (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)
      A mismatch in timing between the release of male and female gametes in external fertilizers may lead to failed fertilization or, under sperm competition, reduced paternity. To quantify the actual synchrony of gamete release and the level of sperm competition we placed video cameras on two spawning grounds of a naturally spawning population of Arctic charr ( Salvelinus alpinus). Females release eggs ...
    • Structural and biochemical characterization of the environmental MBLs MYO-1, ECV-1 and SHD-1 

      Frøhlich, Christopher; Sørum, Vidar; Huber, Sandra; Samuelsen, Ørjan; Berglund, Fanny; Kristiansson, Erik; Kotsakis, Stathis D.; Marathe, Nachiket P.; Larsson, Joakim; Leiros, Hanna-Kirsti S. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-28)
      <i>Background</i> - MBLs form a large and heterogeneous group of bacterial enzymes conferring resistance to β-lactam antibiotics, including carbapenems. A large environmental reservoir of MBLs has been identified, which can act as a source for transfer into human pathogens. Therefore, structural investigation of environmental and clinically rare MBLs can give new insights into structure–activity ...
    • Structural and biochemical characterization of the environmental MBLs MYO-1, ECV-1 and SHD-1 

      Frøhlich, Christopher; Sørum, Vidar; Huber, Sandra; Samuelsen, Ørjan; Berglund, Fanny; Kristiansson, Erik; Kotsakis, Stathis D.; Marathe, Nachiket; Larsson, DG Joakim; Leiros, Hanna-Kirsti Schrøder (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-28)
      Background: MBLs form a large and heterogeneous group of bacterial enzymes conferring resistance to b-lactam antibiotics, including carbapenems. A large environmental reservoir of MBLs has been identified, which can act as a source for transfer into human pathogens. Therefore, structural investigation of environmental and clinically rare MBLs can give new insights into structure–activity relationships ...