Blar i forfatter "Hegstad, Joachim"

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    • The chemotherapeutic drug methotrexate selects for antibiotic resistance 

      Gudmundsdottir, Jonina; Fredheim, Elizabeth G. Aarag; Koumans, Catharina I.M.; Hegstad, Joachim; Tang, Po-Cheng; Andersson, Dan I.; Samuelsen, Ørjan; Johnsen, Pål Jarle (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-12-11)
      Background: Understanding drivers of antibiotic resistance evolution is fundamental for designing optimal treatment strategies and interventions to reduce the spread of antibiotic resistance. Various cytotoxic drugs used in cancer chemotherapy have antibacterial properties, but how bacterial populations are affected by these selective pressures is unknown. Here we test the hypothesis that the widely ...

    • Emergence of vancomycin-resistant enterococci from vancomycin susceptible enterococci in hospitalized patients under antimicrobial therapy 

      Janice, Jessin; Wagner, Theresa Maria; Olsen, Karina; Hegstad, Joachim; Hegstad, Kristin (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-12-19)
      Objectives: Enterococci are opportunistic pathogens with plastic genomes that evolve, acquire, and transmit antimicrobial-resistant determinants such as vancomycin resistance clusters. While vancomycinresistant enterococci (VRE) have emerged as successful nosocomial pathogens, the mechanism by which vancomycin-susceptible enterococci (VSE) transform to VRE in hospitalized patients remains ...

    • 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 ...

    • Piggybacking on Niche Adaptation Improves the Maintenance of Multidrug-Resistance Plasmids 

      Kloos, Julia Maria; Gama, João Alves; Hegstad, Joachim; Samuelsen, Ørjan; Johnsen, Pål Jarle (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-03-24)
      The persistence of plasmids in bacterial populations represents a puzzling evolutionary problem with serious clinical implications due to their role in the ongoing antibiotic resistance crisis. Recently, major advancements have been made toward resolving this “plasmid paradox” but mainly in a nonclinical context. Here, we propose an additional explanation for the maintenance of multidrug‐resistance ...

    • The population structure of vancomycin-resistant and -susceptible Enterococcus faecium in a low-prevalence antimicrobial resistance setting is highly influenced by circulating global hospital-associated clones 

      al Rubaye, Mushtaq Talib Shawi; Janice, Jessin; Bjørnholt, Jørgen; Kacelnik, Oliver; Haldorsen, Bjørg C; Nygaard, Randi Monsen; Hegstad, Joachim; Sundsfjord, Arnfinn Ståle; Hegstad, Kristin (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-09-19)
      Between 2010 and 2015 the incidence of vancomycin-resistant Enterococcus faecium (VREfm) in Norway increased dramatically. Hence, we selected (1) a random subset of vancomycin-resistant enterococci (VRE) from the Norwegian Surveillance System for Communicable Diseases (2010–15; n=239) and (2) Norwegian vancomycin-susceptible E. faecium (VSEfm) bacteraemia isolates from the national surveillance ...