Molecular and epidemiology characterization of carbapenem-resistant Escherichia coli in Hangzhou, China.

INTRODUCTION: With the large-scale use of antibiotics, the detection rate and mortality of carbapenem resistant Escherichia coli (CR-EC) have gradually increased. This study investigated the molecular characteristics and prevalence of CR-EC in order to supplement the isolated data of CR-EC in Hangzhou, China.

METHODOLOGY: The minimal inhibitory concentration was determined by microbroth dilution method. The drug resistance genes were detected by polymerase chain reaction. The transferability of plasmid was verified by the conjugation test and genetic homology was detected by pulsed-field gel electrophoresis. The whole genome was sequenced (WGS) using the Illumina MiSeq technology.

RESULTS: A total of 8 non-duplicated CR-EC isolates were collected, and all exhibited a multidrug-resistant phenotype. Two different New Delhi metallo-β-lactamase (NDM) variants, blaNDM-5 and blaNDM-13, were found with detection rates of 62.5% and 12.5%, respectively. The success rate of conjugation was 100% (6/6). Homology analysis showed that there was no widespread cloning outbreak of CR-EC, and blaNDM-5-ST410 was prevalent in the local area as a dominant group. WGS also indicated the rate of occurrence of resistance genes carrying resistance for more types of antibiotics, as well as exposed potential virulence risks.

CONCLUSIONS: This was a survey on the prevalence and molecular characteristics of CR-EC in Hangzhou. blaNDM-like production combined with extended spectrum beta-lactamase (ESBLs) and/or AmpC was the main resistance mechanism of CR-EC in this area. The dominant blaNDM-5-ST410 requires enhanced attention. The horizontal transformation of plasmids, complex drug resistance, and potential virulence risks also need close attention.