Study On Horizontal Transfer Of The NDM-4 And NDM-5 Metal β-Lactamases Variants In Carbapenem-Resistant Enterobacteriaceae(CRE)

Recently,increased prevalence of Carbapenem-resistant Enterobacteriaceae（CRE）were observed over the world.CRE represents a serious threat to public health.Its increasing prevalence,limited treatment options,and associated high rates of mortality have prompted organizations sush as the CDS and WHO to designate CRE as an urgent threat.New Delhi metal β-lactamase（NDM）,which can hydrolyze all β-lactam antibiotics except monobactams,is one of class B metallo-beta-lactamase that has been identified in multiple species of Enterobacteriaceae in more than 40 countries worldwide.Up to date,17 different NDM variants have been reported in different regions around the world.These variants with amino acid substitutions at 14 positions possess changed enzymatic activities against β-lactam antibiotics.Our previous study reported a high incidence of NDM-1-producing CRE from patients with diffirent clinical diseases in Henan province,following study was conducted to detect the prevalence of different NDM variants in Henan province.Our work revealed seveal important fidings on the prevalence of NDM variants in Henan province: 1.We decribe the first NDM-4-producing E.coli ST410 isolate,which,to our knowledge,is the first case in China,and report the characterization of the bla_NDM-4 harboring IncX3 plasmid.2.The bla_NDM-5-positive CRE isolates were genetically diverse,and the ST167 E.coli might be a potential endemic clone that carrying NDM-5 in Henan province.3.Most of the plasmids carrying NDM-4 or NDM-5 belonged to the IncX3 incompatibility group,indicating IncX3 plasmid might have become a common vehicle for the dissemination of different NDM alleles among Enterobacteriaceae in Henan province.