Abstract
OBJECTIVE: The global emergence of multidrug-resistant Escherichia coli strains, particularly those co-carrying plasmid-mediated colistin and carbapenemase genes, represents a significant public health concern. The coexistence of these resistance determinants severely limits the therapeutic options available for treating infections caused by MDR pathogens. METHODS: Antimicrobial susceptibility testing was performed by broth microdilution assay. Clermont Typing platform was employed to classify the phylogenetic group. The BacWGSTdb 2.0 online platform was utilized to determine sequence types and perform the core genome cgMLST analysis by comparing with publicly available E. coli isolates. Serotype, FimH type, Inc groups and antimicrobial resistance genes were carried out using SerotypeFinder 2.0, CHTyper 1.0, PlasmidFinder 2.1 and ResFinder 3.2 databases, respectively. RESULTS: E. coli SM107 was resistant to nearly all the tested antibiotics excluding nitrofurantoin. The complete genome sequence comprises a single chromosome along with six plasmids and was assigned to sequence type (ST)1011. The bla (NDM-5) gene was discovered in a 119,850 bp IncI1-1-type plasmid with IS26, IS3000, IS30 and IS5 exist downstream of the bla (NDM-5) gene with IS26 situated upstream as a truncated fragment. The mcr-1.1 gene in a 111,450 bp IncI2-type plasmid. cgMLST analysis highlighting the emergence of multidrug-resistant E. coli ST1011 strains that harbor both colistin and carbapenem resistance genes. CONCLUSION: We report the emergence of a ST1011 E. coli strain in China co-carrying the mcr-1.1 and bla (NDM-5) genes. This highlights the urgent need for alternative therapeutic strategies, strengthened antimicrobial stewardship, and enhanced genomic surveillance to curb the dissemination of high-risk resistance plasmids and safeguard the effectiveness of last-resort antibiotics.