Emergence of a blaNDM-5 Carrying IncHI2/IncHI2A Plasmid in a Multidrug Resistant Clinical ST1431 Escherichia coli Strain

Abstract: Carbapenems are the last-resort antibiotics used to treat infections caused by bacterial pathogens. Many bacterial pathogens have evolved to produce NDM carbapenemases to hydrolyze carbapenems, posing a great challenge to public health. In this study, we report a multidrug resistant clinical E. coli strain 673. Strain 673 belongs to sequence type (ST) 1431 and carries several plasmids, p673-blaTEM-1B, p673-blaCTX-M-55, p673-blaNDM-5, p673-13272, and p673-6468. p673-blaNDM-5 is an IncHI2/IncHI2A-type plasmid harboring several antibiotic resistance genes, including bla NDM-5 , strA, strB , and dfrA . The bla NDM-5 gene was surrounded by two IS 26 elements in p673-blaNDM-5, indicating that IS 26 could mediate the integration of bla NDM-5 into p673-blaNDM-5. p673-blaCTX-M-55 is an IncFII-type plasmid harboring fosA, aadA1 , and bla CTX-M-55 . p673-blaTEM-1B is an IncFIB-type plasmid harboring bla TEM-1B and dfrA5 . p673-13272 is a ColRNAI-type plasmid that does not carry any drug resistance genes. This is the first report that a bla NDM-5 -bearing IncHI2/IncHI2A-type plasmid has emerged in a clinical E. coli strain in China. Our findings suggest that IS 26 mediates the integration of bla NDM-5 into p673-blaNDM-5. The spread of bla NDM-5 -bearing plasmids is a clinical challenge and endangers public health. Keywords: NDM-5, IncHI2/IncHI2A plasmid, E. coli