Abstract: Objective To analyze the drug susceptibility,carbapenem resistance determinants and multi-locus sequence types of carbapenem resistant Escherichia coli.Methods Carbapenem-resistant E.coli isolates collected from our hospital were analyzed for the susceptibilities by Vitek 2 Compact.Detection of carbapenem resistance genes was performed by PCR and DNA sequencing,Multi-locus sequence typing was used to analyze the sequence types of bacteria.The transferability of bla_NDM gene was analyzed by conjugation experiment.Results Carbapenem-resistant E.coli were resistant to most of the commonly used antibiotics in clinical therapy.Nine out of 11 carbapenem resistant E.coli isolates were found to carry bla_NDM gene,and two isolates of them were found to carry bla_KPC gene.The results of multilocus sequence typing showed that 11 E.coli isolates were assigned into 7 sequence types (STs),which were ST167(n=3),ST6349(n=1),ST361(n=1),ST6335(n=1),ST617(n=1),ST7016(n=1) and ST354(n=1).The results of conjugation test showed that bla_NDM gene could be transferred,without bla_KPC gene being co-transferred.Conclusion The production of NDM is the main mechanism of E.coli conferring resistance to carbapenem,which is easy to spread among bacteria,infection control measures should therefore be further strengthened.

Key words: Escherichia coli, Carbapenem resistance, Multi-locus sequence typing, bla_NDM