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Genomic Investigation of Two Acinetobacter baumannii Outbreaks in a Veterinary Intensive Care Unit in The Netherlands
Soe Yu Naing1, Joost Hordijk1, Birgitta Duim1
1Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, 3584 CM Utrecht, The Netherlands.
Abstract:
Acinetobacter baumannii is a nosocomial pathogen that frequently causes healthcare-acquired infections. The global spread of multidrug-resistant (MDR) strains with its ability to survive in the environment for extended periods imposes a pressing public health threat. Two MDR A. baumannii outbreaks occurred in 2012 and 2014 in a companion animal intensive care unit (caICU) in the Netherlands. Whole-genome sequencing (WGS) was performed on dog clinical isolates (n = 6), environmental isolates (n = 5), and human reference strains (n = 3) to investigate if the isolates of the two outbreaks were related. All clinical isolates shared identical resistance phenotypes displaying multidrug resistance. Multi-locus Sequence Typing (MLST) revealed that all clinical isolates belonged to sequence type ST2. The core genome MLST (cgMLST) results confirmed that the isolates of the two outbreaks were not related. Comparative genome analysis showed that the outbreak isolates contained different gene contents, including mobile genetic elements associated with antimicrobial resistance genes (ARGs). The time-measured phylogenetic reconstruction revealed that the outbreak isolates diverged approximately 30 years before 2014. Our study shows the importance of WGS analyses combined with molecular clock investigations to reduce transmission of MDR A. baumannii infections in companion animal clinics.
Insights
Two multidrug-resistant Acinetobacter baumannii outbreaks in a companion animal ICU were not related. Whole-genome sequencing revealed distinct genetic profiles, highlighting the need for WGS to prevent transmission.
Area of Science:
- Veterinary Microbiology
- Genomics
- Infectious Diseases
Background:
- Acinetobacter baumannii is a significant nosocomial pathogen causing healthcare-acquired infections.
- Multidrug-resistant (MDR) strains pose a global public health threat due to their environmental persistence.
- Two MDR A. baumannii outbreaks occurred in a companion animal intensive care unit (caICU) in the Netherlands in 2012 and 2014.
Purpose of the Study:
- To investigate the relationship between MDR A. baumannii isolates from two distinct outbreaks in a companion animal ICU.
- To determine if clinical and environmental isolates were linked to the outbreaks.
- To understand the genomic diversity and evolutionary history of outbreak-related A. baumannii strains.
Main Methods:
- Whole-genome sequencing (WGS) of clinical (n=6), environmental (n=5), and human reference (n=3) A. baumannii isolates.
- Multi-locus Sequence Typing (MLST) and core genome MLST (cgMLST) for strain relatedness analysis.
- Comparative genome analysis and time-calibrated phylogenetic reconstruction.
Main Results:
- All clinical isolates exhibited identical multidrug resistance phenotypes and belonged to sequence type ST2.
- cgMLST confirmed that isolates from the 2012 and 2014 outbreaks were not related.
- Comparative genomics identified different gene content, including mobile genetic elements with antimicrobial resistance genes (ARGs), between outbreak isolates.
- Phylogenetic analysis indicated divergence of outbreak isolates approximately 30 years prior to 2014.
Conclusions:
- The two MDR A. baumannii outbreaks in the companion animal ICU were caused by unrelated strains.
- Whole-genome sequencing is crucial for differentiating outbreak sources and understanding transmission dynamics.
- Molecular clock investigations aid in reconstructing the evolutionary history of bacterial pathogens.
- Implementing WGS strategies can help reduce the transmission of MDR A. baumannii in veterinary clinical settings.
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