Genomic epidemiology unravels simultaneous clusters of linezolid-resistant Staphylococcus epidermidis isolated in Austria, 2023–2025
7 affiliations
- 1Institute for Surveillance and Infectious Disease Epidemiology, Austrian Agency for Health and Food Safety
- 2Institute for Medical Microbiology and Hygiene, Austrian Agency for Health and Food Safety
- 3National Reference Center for Antimicrobial Resistance
- 4Ares Genetics GmbH
- 5Institute of Hygiene, University Hospital Muenster and University of Muenster
- 6Institute of Hygiene and Medical Microbiology, Medical University Innsbruck
- 7Medical Faculty, Johannes Kepler University Linz
Abstract
Introduction: Staphylococcus epidermidis is an opportunistic pathogen causing bloodstream and device-associated infections. Due to the use of linezolid (LZD) against infections caused by multidrug-resistant Gram-positive bacteria, the emergence of LZD-resistant S. epidermidis (LRSE) is an increasing concern. This study aimed to characterize genomic clusters, resistance mechanisms, and epidemiological links among LRSE isolates collected during a suspected outbreak in two Austrian hospitals.
Methods: A confirmed case was defined as a patient with LRSE (MIC > 4 mg/L) isolated from clinical or screening samples in Hospital A or Hospital B between March 2023 and April 2025. All isolates underwent whole-genome sequencing (WGS) for typing and identification of resistance determinants. Epidemiological data, including the hospital and ward of detection as well as inter-hospital transfers, were analyzed to explore potential epidemiological links between cases.
Results: A total of 53 LRSE cases were identified, including 22 in Hospital A and 31 in Hospital B. A LZD-resistant Staphylococcus hominis isolate originating from a patient admitted to Hospital B after traveling abroad and no epidemiological link with the LRSE cases was also recovered. Epidemiological and genomic data identified five clusters belonging to three sequence types (ST2, ST5, ST22). Most Cluster 1 cases were detected in Hospital B, especially in the surgical ICU, while Clusters 2–4 were exclusively identified in Hospital A. However, the available epidemiological information was insufficient to determine transmission direction or identify the origin of the clusters. Forty-five of 53 LRSE isolates displayed high-level LZD resistance (MIC ≥48 mg/L). Distinct resistance-associated mutations were identified in each ST, including G2576U in ST2 isolates, C2534U and U2504A in ST22 isolates, and characteristic alterations in ribosomal proteins L3 and L4.
Conclusion: Genomic analysis identified five distinct LRSE clusters belonging to three STs and revealed ST-specific resistance mutations, suggesting multiple independent evolutionary pathways to LZD resistance. However, limited epidemiological information, including incomplete data on LZD administration and patient movements, prevented definitive assessment of transmission dynamics. Our findings demonstrate the utility of WGS for the detection and characterization of LRSE clusters and highlight the importance of comprehensive epidemiological data for interpreting genomic links.
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BibTeX
@article{rosel2026genomic,
title = {{Genomic epidemiology unravels simultaneous clusters of linezolid-resistant Staphylococcus epidermidis isolated in Austria, 2023–2025}},
author = {Adriana Cabal Rosel and Heidrun Kerschner and Johannes Weinberger and Anna Stöger and Kathrin Lippert and Beatriz Daza Prieto and Alexander Mellmann and Petra Apfalter and Werner Ruppitsch and Rainer Hartl},
journal = {Frontiers in Microbiology},
year = {2026},
month = oct,
doi = {10.3389/fmicb.2026.1934085},
url = {https://www.frontiersin.org/articles/10.3389/fmicb.2026.1934085/full},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Genomic epidemiology unravels simultaneous clusters of linezolid-resistant Staphylococcus epidermidis isolated in Austria, 2023–2025
AU - Adriana Cabal Rosel
AU - Heidrun Kerschner
AU - Johannes Weinberger
AU - Anna Stöger
AU - Kathrin Lippert
AU - Beatriz Daza Prieto
AU - Alexander Mellmann
AU - Petra Apfalter
AU - Werner Ruppitsch
AU - Rainer Hartl
PY - 2026
DA - 2026/10/20
JO - Frontiers in Microbiology
DO - 10.3389/fmicb.2026.1934085
UR - https://www.frontiersin.org/articles/10.3389/fmicb.2026.1934085/full
AB - Introduction: Staphylococcus epidermidis is an opportunistic pathogen causing bloodstream and device-associated infections. Due to the use of linezolid (LZD) against infections caused by multidrug-resistant Gram-positive bacteria, the emergence of LZD-resistant S. epidermidis (LRSE) is an increasing concern. This study aimed to characterize genomic clusters, resistance mechanisms, and epidemiological links among LRSE isolates collected during a suspected outbreak in two Austrian hospitals. Methods: A confirmed case was defined as a patient with LRSE (MIC > 4 mg/L) isolated from clinical or screening samples in Hospital A or Hospital B between March 2023 and April 2025. All isolates underwent whole-genome sequencing (WGS) for typing and identification of resistance determinants. Epidemiological data, including the hospital and ward of detection as well as inter-hospital transfers, were analyzed to explore potential epidemiological links between cases. Results: A total of 53 LRSE cases were identified, including 22 in Hospital A and 31 in Hospital B. A LZD-resistant Staphylococcus hominis isolate originating from a patient admitted to Hospital B after traveling abroad and no epidemiological link with the LRSE cases was also recovered. Epidemiological and genomic data identified five clusters belonging to three sequence types (ST2, ST5, ST22). Most Cluster 1 cases were detected in Hospital B, especially in the surgical ICU, while Clusters 2–4 were exclusively identified in Hospital A. However, the available epidemiological information was insufficient to determine transmission direction or identify the origin of the clusters. Forty-five of 53 LRSE isolates displayed high-level LZD resistance (MIC ≥48 mg/L). Distinct resistance-associated mutations were identified in each ST, including G2576U in ST2 isolates, C2534U and U2504A in ST22 isolates, and characteristic alterations in ribosomal proteins L3 and L4. Conclusion: Genomic analysis identified five distinct LRSE clusters belonging to three STs and revealed ST-specific resistance mutations, suggesting multiple independent evolutionary pathways to LZD resistance. However, limited epidemiological information, including incomplete data on LZD administration and patient movements, prevented definitive assessment of transmission dynamics. Our findings demonstrate the utility of WGS for the detection and characterization of LRSE clusters and highlight the importance of comprehensive epidemiological data for interpreting genomic links.
SN - 1664-302X
ER -