Emergence of Dual β-lactam and Colistin Resistance via blaFRI-8and mcr-10.2 co-carriage on an IncFII Family Plasmid in Enterobacter vonholyi
Abstract
Objectives
Enterobacter vonholyiisolate E323169 represents a rare case of co-carriage of the antimicrobial resistance genes (ARGs)blaFRI-8,mcr-10.2. isolated from a clinical rectal swab. E323169 is one of only 12 availableE. vonholyigenomes. To date, and across over two million pathogenic genomes scanned, only three harbourblaFRI-8and two encodemcr-10.2, yet none exhibit both genes together. This study analyzes the genomic, phenotypic and epidemiological importance of this rare co-occurrence.
Methods
Species-ID for E323169 was assigned by MALDI-TOF and then re-assigned and confirmed using a multifactorial genomic workflow. Antimicrobial susceptibilities were determined by MIC assay. The genome of E323169 was sequenced on an Illumina-NextSeq-1000, assembled, and annotated for ARGs, virulence factors, and plasmid replicons detection. Comparative phylogenomics used 12E. vonholyiRefSeq assemblies, and NCBI metadata were analysed for plasmid distributions ofblaFRI-8andmcr-10.2.
Results
E323169 carried six ARGs: four chromosomally encoded (blaACT-91, fosA, oqxA10, oqxB9) and two plasmid-borne (blaFRI-8andmcr-10.2) co-located on IncFII(p14)_1_p14 replicon. Additional plasmid replicons: Col(MG828)_1 and ColRNAI_1 were also identified. By mining the NCBI Pathogen Detection pipeline, we identifiedblaFRI-8on IncFII replicon inE. asburiaeJBIWA002, andmcr-10.2on a multi-replicon (IncFIB/IncFII) plasmid inE. kobei11778-yvys.
Conclusion
This report documents the firstE. vonholyiisolate co-harboringblaFRI-8andmcr-10.2on a single IncFII family plasmid, showing the widening host range of plasmid-mediated resistance to carbapenems/colistin. No prior similar co-occurrences reported, underscoring its rarity. These findings highlight the urgent need for enhanced clinical screening and genomic surveillance to curb the spread.
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