Lotte Jelsbak
Associate Professor at Roskilde University
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About
Dr. Lotte Jelsbak is an Associate Professor at Roskilde University, Denmark. Her research focuses on antimicrobial resistance, genomics of pathogenic bacteria, and the effects of environmental factors on bacterial virulence. Recent publications include studies on Staphylococcus saprophyticus, Salmonella enterica, and multidrug-resistant Escherichia coli, contributing to a deeper understanding of bacterial behavior and resistance mechanisms.
Positions (1)
Lotte Jelsbak
Roskilde University
10 months ago
The Department of Science and Environment at Roskilde University is seeking a postdoctoral researcher in Molecular Microbiology, with a focus on antimicrobial resistance (AMR) mechanisms, starting April 1, 2026 or as soon as possible thereafter. This 3-year position is funded by the Independent Research Fund Denmark (DFF) and will be supervised by Associate Professor Lotte Jelsbak. The research group investigates molecular mechanisms of AMR and virulence in enteric pathogens, primarily E. coli and Salmonella Typhimurium, aiming to uncover novel resistance mechanisms and identify new antimicrobial targets. The group employs a range of techniques including molecular biology, bacterial genetics, chemical analyses, and omics approaches, and collaborates closely with clinical researchers and other departments. The postdoc will lead research on AMR in E. coli, specifically investigating a novel mechanism called heteroresistance. The position includes a planned 3-month research visit to Saarland University, Germany, in the third year, and some teaching responsibilities. The successful candidate will be expected to work independently, contribute innovative research ideas, mentor students, and actively participate in the dynamic and interdisciplinary research environment. Applicants must have a PhD in molecular microbiology or a closely related field, with expertise in genetic engineering, bacterial model organisms, omics, AMR mechanisms, and data analysis (R-Studio or similar). Strong English communication skills, organizational abilities, and a record of peer-reviewed publications are required. The Molecular & Medical Biology (MMB) Section, where the group is based, offers state-of-the-art laboratory facilities and a collaborative environment spanning molecular microbiology, cell biology, drug development, and more. The department values diversity and encourages applications from all qualified candidates. Applications must be submitted online in English by December 14, 2025, and should include a cover letter, CV, educational documentation, publication list, and up to five relevant scientific works. For more information, contact Associate Professor Lotte Jelsbak at [email protected].
10 months ago
Articles (10)
Year:
2025
Objectives An Escherichia coli isolate, WGS1363, showed resistance to piperacillin/tazobactam but susceptibility to cephalosporins and contained a previously unrecognized β-lactamase, CTX-M-255, as the only acquired β-lactamase. CTX-M-255 was identical to CTX-M-27 except for a G239S substitution. Here, we characterize the hydrolytic spectrum of CTX-M-255 and a previously reported β-lactamase, CTX-M-178, also containing a G239S substitution and compare it to their respective parental enzymes, CTX-M-27 and CTX-M-15. Methods All β-lactamase genes were expressed in E. coli TOP10 and MICs to representative β-lactam-antibiotics were determined. Furthermore, blaCTX-M-15, blaCTX-M-27, blaCTX-M-178 and blaCTX-M-255 with C-terminal His-tag fusions were affinity purified for enzyme kinetic assays determining Michaelis–Menten kinetic parameters against representative β-lactam-antibiotics and IC50s of clavulanate, sulbactam, tazobactam and avibactam. Results TOP10-transformants expressing blaCTX-M-178 and blaCTX-M-255 showed resistance to penicillin/β-lactamase combinations and susceptibility to cephalothin and cefotaxime in contrast to transformants expressing blaCTX-M-15 and blaCTX-M-27. Determination of enzyme kinetic parameters showed that CTX-M-178 and CTX-M-255 both lacked hydrolytic activity against cephalosporins and showed impaired hydrolytic efficiency against penicillin antibiotics compared to their parental enzymes. Both enzymes appeared more active against piperacillin compared to benzylpenicillin and ampicillin. Compared to their parental enzymes, IC50s of β-lactamase-inhibitors were increased more than 1000-fold for CTX-M-178 and CTX-M-255. Conclusions CTX-M-178 and CTX-M-255, both containing a G239S substitution, conferred resistance to piperacillin/tazobactam and may be characterized as inhibitor-resistant CTX-M β-lactamases. Inhibitor resistance was accompanied by loss of activity against cephalosporins and monobactams. These findings add to the necessary knowledge base for predicting antibiotic susceptibility from genotypic data.
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2024
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2023
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2023
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2023
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2022
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2022
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2021
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2021
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2020
Collaborators (13)
Karen Angeliki Krogfelt
Roskilde University
Martin Schou Pedersen
Copenhagen University Hospital
Lucie Etienne-Mesmin
Université Clermont Auvergne
ole skovgaard
VIP, Associate Professor Emeritus
Roskilde University
Henrik Christensen
Københavns Universitet
Jens Peter Christensen
Københavns Universitet
Andreas Munk Petersen
MD, clinical associate Professor, Ph.D., DMSc
Hvidovre Hospital
Opeyemi Lawal
Assistant Professor
University of Windsor
Paulo Paixão
-
John Elmerdahl Olsen
Københavns Universitet
Elora Fournier
Assistant professor (maître de conférence) / Dr
Université Clermont Auvergne
Line Elnif Thomsen
Associate Professor
University of Copenhagen
Kristian Schønning
Copenhagen University Hospital
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