
Ørjan Samuelsen
Oskar Ljungquist,
Bjørg Haldorsen,
Anna Kaarina Pöntinen,
Jessin Janice,
Ellen Haldis Josefsen,
Petter Elstrøm
et al.:
Nationwide, population-based observational study of the molecular epidemiology and temporal trend of carbapenemase-producing Enterobacterales in Norway, 2015 to 2021
Paul Christoffer Lindemann,
Torunn Pedersen,
Dorthea Hagen Oma,
Jessin Janice,
Fredrik Grøvan,
Ghantous Milad Chedid
et al.:
Intraregional hospital outbreak of OXA-244-producing Escherichia coli ST38 in Norway, 2020
Marius Linkevicius,
Rémy A Bonnin,
Erik Alm,
Olov Svartström,
Petra Apfalter,
Rainer Hartl
et al.:
Rapid cross-border emergence of NDM-5-producing Escherichia coli in the European Union/European Economic Area, 2012 to June 2022
Greta Petazzoni,
Greta Bellinzona,
Cristina Merla,
Marta Corbella,
Vincenzina Monzillo,
Ørjan Samuelsen
et al.:
The COVID-19 Pandemic Sparked off a Large-Scale Outbreak of Carbapenem-Resistant Acinetobacter baumannii from the Endemic Strains at an Italian Hospital
Sergio Arredondo Alonso,
George Blundell-Hunter,
Zuyi Fu,
Rebecca Ashley Gladstone,
Alfred Fillol-Salom,
Jessica Loraine
et al.:
Evolutionary and functional history of the Escherichia coli K1 capsule
Sergio Arredondo Alonso,
Rebecca Ashley Gladstone,
Anna Kaarina Pöntinen,
João Alves Gama,
Anita C. Schürch,
Val F. Lanza
et al.:
Mge-cluster: a reference-free approach for typing bacterial plasmids
NAR Genomics and Bioinformatics 2023 DOI
Pete Kinross,
Carlo Gagliotti,
Hanna Merk,
Diamantis Plachouras,
Dominique L. Monnet,
Liselotte Diaz Högberg
et al.:
Large increase in bloodstream infections with carbapenem-resistant Acinetobacter species during the first 2 years of the COVID-19 pandemic, EU/EEA, 2020 and 2021
Eurosurveillance 2022 DOI
Tommi Mäklin,
Harry Arthur Frank Wright Thorpe,
Anna Kaarina Pöntinen,
Rebecca Ashley Gladstone,
Yan Shao,
Maiju Pesonen
et al.:
Strong pathogen competition in neonatal gut colonisation
Kenneth Lindstedt,
Dorota Julia Buczek,
Torunn Annie Pedersen,
Erik Hjerde,
Niclas Peter Raffelsberger,
Yutaka Suzuki
et al.:
Detection of Klebsiella pneumoniae human gut carriage: a comparison of culture, qPCR, and whole metagenomic sequencing methods
Aleksandra Jakovljev,
Jan Egil Afset,
Kjersti Haugum,
Harald Otto Steinum,
Torunn Gresdal Rønning,
Ørjan Samuelsen
et al.:
Phenotypic and genotypic characterisation of thymine auxotrophy in Escherichia coli isolated from a patient with recurrent bloodstream infection
Vidar Sørum,
Emma Lu Øynes,
Anna Sollied Møller,
Klaus Harms,
Ørjan Samuelsen,
Nicole L. Podnecky
et al.:
Evolutionary Instability of Collateral Susceptibility Networks in Ciprofloxacin-Resistant Clinical Escherichia coli Strains
Tommi Mäklin,
Teemu Kallonen,
Jarno Alanko,
Ørjan Samuelsen,
Kristin Hegstad,
Veli Mäkinen
et al.:
Bacterial genomic epidemiology with mixed samples
Jonina Gudmundsdottir,
Elizabeth G. Aarag Fredheim,
Catharina I.M. Koumans,
Joachim Hegstad,
Po-Cheng Tang,
Dan I. Andersson
et al.:
The chemotherapeutic drug methotrexate selects for antibiotic resistance
Jessin Janice,
Nicholas Agyepong,
Alex Owusu-Ofori,
Usha Govinden,
Sabiha Essack,
Ørjan Samuelsen
et al.:
Carbapenem resistance determinants acquired through novel chromosomal integrations in extensively drug-resistant pseudomonas aeruginosa
Rebecca Ashley Gladstone,
Alan McNally,
Anna Kaarina Pöntinen,
Gerry Tonkin-Hill,
John A. Lees,
Kusti Onni Skytén
et al.:
Emergence and dissemination of antimicrobial resistance in Escherichia coli causing bloodstream infections in Norway in 2002–17: a nationwide, longitudinal, microbial population genomic study
Niclas Peter Raffelsberger,
Marit Andrea Klokkhammer Hetland,
Kristian Svendsen,
Lars Småbrekke,
Iren Høyland Löhr,
Lotte Andreassen
et al.:
Gastrointestinal carriage of Klebsiella pneumoniae in a general adult population: a cross-sectional study of risk factors and bacterial genomic diversity
Julia Kloos,
João A Gama,
Joachim Hegstad,
Ørjan Samuelsen,
Pål J Johnsen
:
Piggybacking on Niche Adaptation Improves the Maintenance of Multidrug-Resistance Plasmids
Sergio Arredondo Alonso,
Anna Kaarina Pöntinen,
Francois Pierre Alexandre Cleon,
Rebecca Ashley Gladstone,
Anita C. Schürch,
Pål Jarle Johnsen
et al.:
A high-throughput multiplexing and selection strategy to complete bacterial genomes
Supathep Tansirichaiya,
Richard N. Goodman,
Xinyu Guo,
Issra Bulgasim,
Ørjan Samuelsen,
Mohammed Al-Haroni
et al.:
Intracellular Transposition and Capture of Mobile Genetic Elements following Intercellular Conjugation of Multidrug Resistance Conjugative Plasmids from Clinical Enterobacteriaceae Isolates
Aasmund Fostervold,
Marit Andrea Klokkhammer Hetland,
Ragna-Johanne Bakksjø,
Eva Bernhoff,
Kathryn E. Holt,
Ørjan Samuelsen
et al.:
A nationwide genomic study of clinical Klebsiella pneumoniae in
Norway 2001–15: introduction and spread of ESBLs facilitated by
clonal groups CG15 and CG307
Christopher Frøhlich,
João Alves Gama,
Klaus Harms,
Viivi H. A. Hirvonen,
Bjarte Aarmo Lund,
Marc W. van der Kamp
et al.:
Cryptic β-Lactamase Evolution Is Driven by Low β-Lactam Concentrations
Catherine Ludden,
Felix Lötsch,
Erik Alm,
Narender Kumar,
Karin Johansson,
Barbara Albiger
et al.:
Cross-border spread of blaNDM-1- and blaOXA-48-positive Klebsiella pneumoniae: a European collaborative analysis of whole genome sequencing and epidemiological data, 2014 to 2019
Joao Pedro Alves Gama,
Julia Maria Kloos,
Pål Jarle Johnsen,
Ørjan Samuelsen
:
Host dependent maintenance of a blaNDM-1-encoding plasmid in clinical Escherichia coli isolates
Julia Maria Kloos,
Joao Pedro Alves Gama,
Pål Jarle Johnsen,
Ørjan Samuelsen
:
Host dependent maintenance of a blaNDM-1-encoding plasmid in clinical Escherichia coli isolates
Scientific Reports 2020 DOI
Torunn Annie Pedersen,
Marit Gjerde Tellevik,
Øyvind Kommedal,
Paul Christoffer Lindemann,
Sabrina John Moyo,
Jessin Janice James Peter
et al.:
Horizontal plasmid transfer among klebsiella pneumoniae isolates is the key factor for dissemination of extended-spectrum β-lactamases among children in Tanzania
Hanna-Kirsti S. Leiros,
Ane Molden Thomassen,
Ørjan Samuelsen,
Carl-Fredrik Flach,
Stathis D. Kotsakis,
Joakim Larsson
:
Structural insights into the enhanced carbapenemase
efficiency of OXA-655 compared to OXA-10
Christopher Frøhlich,
Vidar Sørum,
Sandra Huber,
Ørjan Samuelsen,
Fanny Berglund,
Erik Kristiansson
et al.:
Structural and biochemical characterization of the environmental MBLs MYO-1, ECV-1 and SHD-1
Ørjan Samuelsen,
Ove Alexander Høgmoen Åstrand,
Christopher Frøhlich,
Adam Heikal,
Susann Skagseth,
Trine Josefine Olsen Carlsen
et al.:
ZN148 Is a Modular Synthetic Metallo-beta-Lactamase Inhibitor That Reverses Carbapenem Resistance in Gram-Negative Pathogens In Vivo
Christopher Frøhlich,
Vidar Sørum,
Ane Molden Thomassen,
Pål Jarle Johnsen,
Hanna-Kirsti S. Leiros,
Ørjan Samuelsen
:
OXA-48-Mediated Ceftazidime-Avibactam Resistance Is Associated with Evolutionary Trade-Offs
Petter Elstrøm,
Elisabeth Astrup,
Kristin Hegstad,
Ørjan Samuelsen,
Hege Enger,
Oliver Kacelnik
:
The fight to keep resistance at bay, epidemiology of carbapenemase producing organisms (CPOs), vancomycin resistant enterococci (VRE) and methicillin resistant Staphylococcus aureus (MRSA) in Norway, 2006-2017
Anthony Prandina,
Sylvie Radix,
Marc Le Borgne,
Lars Petter Jordheim,
Zineb Bousfiha,
Christopher Fröhlich
et al.:
Synthesis and biological evaluation of new dipicolylamine zinc chelators as metallo-β-lactamase inhibitors
Geir Kildahl-Andersen,
Christian Schnaars,
Anthony Prandina,
Sylvie Radix,
Marc Le Borgne,
Lars Petter Jordheim
et al.:
Synthesis and biological evaluation of zinc chelating compounds as metallo-β-lactamase inhibitors
MedChemComm 2019 DOI
Ilya Nikolaevich Zykov,
Niels Frimodt-Møller,
Lars Småbrekke,
Arnfinn Sundsfjord,
Ørjan Samuelsen
:
Efficacy of mecillinam against clinical multidrug-resistant Escherichia coli in a murine urinary tract infection model
Nicole L. Podnecky,
Elizabeth Aarag,
Julia Maria Kloos,
Vidar Sørum,
Raul Primicerio,
Adam Paul Roberts
et al.:
Conserved collateral antibiotic susceptibility networks in diverse clinical strains of Escherichia coli.
Marit Hetland,
Mia Angelique Winkler,
Thomas D Stanton,
Ryan R. Wick,
Margaret MC Lam,
Aasmund Fostervold
et al.:
Klebsiella pneumoniae ecology and antimicrobial resistance in a One Health perspective
2023
Julia Maria Kloos,
Lea Jänisch,
Anna Kaarina Pöntinen,
Ørjan Samuelsen,
Pål Jarle Johnsen,
Jukka Corander
et al.:
Different metabolic proficiency among dominant ExPEC lineages
2022
Christopher Frøhlich,
Vidar Sørum,
Nobuhiko Tokuriki,
Ørjan Samuelsen
:
Evolution of ß-lactamase mediated cefiderocol resistance
2022
Pål Jarle Johnsen,
Elizabeth G Aarag Fredheim,
Ørjan Samuelsen,
Klaus Harms
:
The role of drugs used in cancer chemotherapy as drivers of antibiotic resistance evolution in Escherichia coli
2022
Rebecca Ashley Gladstone,
Alan McNally,
Pål Jarle Johnsen,
Ørjan Samuelsen,
Jukka Corander
:
Antimicrobial resistance genes and clonal success in Escherichia coli isolates causing bloodstream infection – Authors’ reply
Lancet Microbe 2021 DOI
Bjørg Haldorsen,
Jessin Janice,
Ørjan Samuelsen
:
Evaluation of the Amplex eazyplex® SuperBug Acineto test for detection of acquired OXA and NDM carbapenemases in Acinetobacter spp.
Journal of Global Antimicrobial Resistance 2021 DOI
João Alves Gama,
Julia Maria Kloos,
Joachim Hegstad,
Ørjan Samuelsen,
Pål Jarle Johnsen
:
Plasmid cost alleviation as a consequence of niche-adaptation
2021
Julia Maria Kloos,
João Alves Gama,
Joachim Hegstad,
Ørjan Samuelsen,
Pål Jarle Johnsen
:
Plasmid Cost Alleviation By Hitchhiking On Niche-adaptation
2021
Julia Maria Kloos,
Joao Pedro Alves Gama,
Joachim Hegstad,
Ørjan Samuelsen,
Pål Jarle Johnsen
:
E. coli Niche Adaptation Improves Plasmid Maintenance
2021
Christopher Frøhlich,
Hanna-Kirsti S. Leiros,
Pål Jarle Johnsen,
Ørjan Samuelsen
:
Sub-inhibitory concentrations of ceftazidime drive evolution of the OXA-48 carbapenemase
2019
Christopher Frøhlich,
Pål Jarle Johnsen,
Hanna-Kirsti Schrøder Leiros,
Ørjan Samuelsen
:
Evolution of OXA-48 under sub-MIC conditions
2019
Vidar Sørum,
Anna Sollied Møller,
Pål Jarle Johnsen,
Ørjan Samuelsen,
Sören Abel,
Nicole L. Podnecky
:
Evolutionary stability of collateral effects in ciprofloxacin resistant clinical Escherichia coli strains
2019
Vidar Sørum,
Anna Sollied Møller,
Sören Abel,
Ørjan Samuelsen,
Nicole L. Podnecky,
Pål Jarle Johnsen
:
Evolutionary stability of collateral effects in ciprofloxacin resistant clinical Escherichia coli strains
2019
Vidar Sørum,
Emma Lu Øynes,
Anna Møller,
Nicole L. Podnecky,
Sören Abel,
Ørjan Samuelsen
et al.:
Evolutionary stability of collateral susceptibility networks in clinical Escherichia coli strains
2019
Julia Maria Kloos,
Joao Pedro Alves Gama,
Ørjan Samuelsen,
Pål Jarle Johnsen
:
Klebsiella pneumoniae MDR-encoding plasmids in clinical isolates of uropathogenic Escherichia coli: plasmid-host co-evolution and its effect on fitness cost of plasmid-mediated resistance
2018
Julia Maria Kloos,
Joao Pedro Alves Gama,
Ørjan Samuelsen,
Pål Jarle Johnsen
:
Plasmid-host co-evolution of Klebsiella pneumoniae MDR-encoding plasmids in clinical isolates of uropathogenic Escherichia coli: effect on fitness cost of plasmid-mediated resistance
2018
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Research interests
Through my positions as Professor II at the Microbial Pharmacology and Population Biology Research Group and as senior scientist at the Norwegian National Advisory Unit on Detection of Antimicrobial Resistance my research focuses broadly on the following topics molecular epidemiology, evaluation of diagnostic methods, biochemical and structural characterization of β-lactamases, development of β-lactamase inhibitors and the evolutionary aspects and transmission dynamics of resistance plasmids.