PhD Scientific Days 2026

Poster Session 1.D - Pathological and Oncological Sciences

Genomic Investigation and Comparative Analysis of European High-Risk Clone of Acinetobacter baumannii ST2

Name of the presenter

Hummel, David

Institute/workplace of the presenter

Institute of Medical Microbiology, Semmelweis University

Authors

David Hummel¹, Janos Juhasz^1,2, Katalin Kamotsay³, Katalin Kristof⁴, Basil Britto Xavier^5,6, Sien De Koster⁷, Dora Szabo^1,8,9, Bela Kocsis¹
1: Institute of Medical Microbiology, Semmelweis University, 1089 Budapest, Hungary
2: Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, 1083 Budapest, Hungary
3: Central Microbiology Laboratory, National Institute of Hematology and Infectious Disease, Central Hospital of Southern-Pest, 1097 Budapest, Hungary
4: Institute of Laboratory Medicine, Semmelweis University, 1083 Budapest, Hungary
5: Laboratory of Medical Microbiology, University of Antwerp, 2610 Antwerpen, Belgium
6: Department of Medical Microbiology and Infection Control, University of Groningen, University Medical Center Groningen, 9713 Groningen, The Netherlands
7: Microbiology Department, Antwerp University Hospital (UZA), 2650 Edegem, Belgium
8: HUN-REN-SU Human Microbiota Research Group, 1052 Budapest, Hungary
9: Department of Neurosurgical and Neurointervention, Semmelweis University, 1085 Budapest, Hungary

Text of the abstract

Introduction: Multidrug-resistant Acinetobacter baumannii is a major concern in healthcare institutions worldwide. This study aimed to characterize A. baumannii isolates from Hungary and compare them with other European strains, focusing on virulence factors and antibiotic resistance genes.
Aims: Genomic analysis of antibiotic resistance genes and virulence factor genes of 19 Hungarian A. baumannii samples along with other European isolates and comparison of their genetic armamentum and clades.
Methods: Whole-genome sequencing (WGS) was performed on 19 multidrug-resistant A. baumannii isolates from two hospitals in Budapest. The results were analyzed alongside data from 433 European A. baumannii isolates from the Pathogenwatch database.
Results: Among the 19 Hungarian isolates, 12 belonged to sequence type ST2 and 7 to ST636. Of the 12 ST2 isolates, 11 carried blaOXA-23 and blaOXA-58 genes, while ST636 uniformly carried blaOXA-72. Core genome MLST revealed 3 subgroups within ST2: 10 strains of ST2 belonged to cgMLST906, one strain to cgMLST458, and one strain to cgMLST1320. Virulence gene profiles differed between ST2 and ST636, with OmpA present only in ST2, whereas many other virulence factors were present in all strains. Analysis of European isolates showed that ST2 was the most prevalent (47.8%), which was widespread across Europe, followed by ST94 (12.2%), typical in the United Kingdom, and ST636 (6.6%), mostly from Eastern Europe.
Conclusions: This study provides insights into the genomic diversity of A. baumannii in Europe, highlighting the dominance of the ST2 high-risk clone. The analysis utilizing cgMLST offers a more precise identification in relation to antibiotic resistance genes and virulence factor genes, highlighting the importance of the application of WGS for the study of MDR A. baumannii clones, which has implications for the surveillance and control of this important nosocomial pathogen.
Funding: This study was supported by HUN-REN-SU, Human Microbiota Study Group No “0272”, and by the European Union’s Horizon 2020 research and innovation program (952491-AmReSu). B.K. was supported by the János Bolyai Scholarship (BO/00286/22/5) of the Hungarian Academy of Sciences.