Emergence of a Carrying IncHI2/IncHI2A Plasmid in a Multidrug Resistant Clinical ST1431 Strain.

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 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 , , and . The gene was surrounded by two IS elements in p673-blaNDM-5, indicating that IS could mediate the integration of into p673-blaNDM-5. p673-blaCTX-M-55 is an IncFII-type plasmid harboring , and . p673-blaTEM-1B is an IncFIB-type plasmid harboring and . p673-13272 is a ColRNAI-type plasmid that does not carry any drug resistance genes. This is the first report that a -bearing IncHI2/IncHI2A-type plasmid has emerged in a clinical strain in China. Our findings suggest that IS mediates the integration of into p673-blaNDM-5. The spread of -bearing plasmids is a clinical challenge and endangers public health.