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The Virulence of S. marcescens Strains Isolated From Contaminated Blood Products Is Divergent in the C. elegans
Alexander Diamandas1, Mikhail R Razon1, Sandra Ramirez-Arcos2,3
1Department of Microbiology, Faculty of Science, University of Manitoba, Winnipeg, MB, Canada.
Abstract:
Bacterial contamination of platelet concentrates (PCs) can occur during blood donation or PC processing, necessitating routine screening to identify contaminated products in efforts to prevent adverse transfusion reactions in recipient patients. Serratia marcescens is a common bacterial contaminant, and its resilient nature coupled with genetic promiscuity imbue this environmental bacterium with resistance to disinfectants and antibiotics enhancing bacterial virulence. In this study, we aim to understand adaptive survival mechanisms through genetic characterization of two S. marcescens strains, CBS11 and CBS12, isolated from PCs by Canadian Blood Services. Genomic analyses of the two strains indicated that CBS11 has one chromosome and one plasmid (pAM01), whereas CBS12 has no plasmids. Phylogenetic analyses show that CBS11 and CBS12 are non-clonal strains, with CBS11 clustering closely with clinical strain CAV1492 and less so with environmental strain PWN146, and CBS12 clustering with a clinical strain AR_0027. Interestingly, pAM01 was most closely related to PWN146p1, a plasmid found in S. marcescens PWN146 strain associated with pinewood nematode Bursaphelenchus xylophilus. Lastly, the genomic diversity of CBS11 and CBS12 was not reflected in the antibiotic resistance profiles as they were remarkably similar to one another, but was reflected in the virulence phenotypes assessed in the Caenorhabditis elegans nematode infection model, with CBS11 being more virulent then CBS12. Taken together, we suggest that S. marcescens environmental isolates that feature evolutionary diverse genomics are better equipped to adapt and thrive in varied environments, such as that of PCs, and therefore is as much of a concern as multi-drug resistance for human infection potential.
Insights
Genomic diversity in Serratia marcescens strains isolated from platelet concentrates influences virulence, not antibiotic resistance. Understanding these adaptive survival mechanisms is crucial for preventing transfusion reactions.
Area of Science:
- Microbiology
- Genomics
- Infectious Disease
Background:
- Bacterial contamination of platelet concentrates (PCs) poses a risk for transfusion reactions.
- Serratia marcescens is a common contaminant with inherent resistance and virulence factors.
- Routine screening is essential to ensure blood product safety.
Purpose of the Study:
- To investigate the adaptive survival mechanisms of Serratia marcescens strains from PCs.
- To perform genetic characterization and phylogenetic analysis of two S. marcescens strains, CBS11 and CBS12.
- To correlate genomic diversity with antibiotic resistance and virulence phenotypes.
Main Methods:
- Whole-genome sequencing and analysis of S. marcescens strains CBS11 and CBS12.
- Plasmid analysis and identification.
- Phylogenetic analysis using comparative genomics.
- Antibiotic resistance profiling.
- Virulence assessment using the Caenorhabditis elegans infection model.
Main Results:
- Strain CBS11 possesses a chromosome and a plasmid (pAM01), while CBS12 lacks plasmids.
- Phylogenetic analysis revealed CBS11 and CBS12 are non-clonal, with distinct clinical and environmental associations.
- Plasmid pAM01 shows close relation to a plasmid found in S. marcescens associated with Bursaphelencus xylophilus.
- Antibiotic resistance profiles were similar between CBS11 and CBS12, despite genomic differences.
- Significant differences in virulence were observed, with CBS11 exhibiting higher virulence in the C. elegans model.
Conclusions:
- Genomic diversity in environmental S. marcescens isolates contributes to adaptability in varied environments like PCs.
- Evolutionary diverse genomics, rather than solely multi-drug resistance, enhances the potential for human infection.
- These findings highlight the importance of considering genomic adaptability in risk assessment for bacterial contaminants in blood products.
