Genetic characterization of bla(NDM)-harboring plasmids in carbapenem-resistant Escherichia coli from Myanmar

The bacterial enzyme New Delhi metallo-β-lactamase hydrolyzes almost all β-lactam antibiotics, including carbapenems, which are drugs of last resort for severe bacterial infections. The spread of carbapenem-resistant Enterobacteriaceae that carry the New Delhi metallo-β-lactamase gene, bla(NDM), poses a serious threat to public health. In this study, we genetically characterized eight carbapenem-resistant Escherichia coli isolates from a tertiary care hospital in Yangon, Myanmar. The eight isolates belonged to five multilocus-sequence types and harbored multiple antimicrobial-resistance genes, resulting in resistance against nearly all of the antimicrobial agents tested, except colistin and fosfomycin. Nine plasmids harboring bla(NDM) genes were identified from these isolates. Multiple bla(NDM) genes were found in the distinct Inc-replicon types of the following plasmids: an IncA/C(2) plasmid harboring bla(NDM-1) (n = 1), IncX3 plasmids harboring bla(NDM-4) (n = 2) or bla(NDM-7) (n = 1), IncFII plasmids harboring bla(NDM-4) (n = 1) or bla(NDM-5) (n = 3), and a multireplicon F plasmid harboring bla(NDM-5) (n = 1). Comparative analysis highlighted the diversity of the bla(NDM)-harboring plasmids and their distinct characteristics, which depended on plasmid replicon types. The results indicate circulation of phylogenetically distinct strains of carbapenem-resistant E. coli with various plasmids harboring bla(NDM) genes in the hospital.