Antimicrobial-resistant Mechanism And Homoloygy Analysis Of Carbapenem-resistant Escherichia Coli

Purposes:Investigating the mechanism of drug resistance and homology of carbapenems towards the isolated Escherichia coli.Methods:We isolated 112 Escherichia coli from clinical samples from Jan 2016 to Mar 2016,By using Vitek 2-compact or traditional bacterial isolation and drug sensitivity method,6 carbapenems resistance species were isolated.The phenotype of those isolated species were determined by EDTA synergy test and modified Hodge test.Then the carbapenems enzyme genes(blaKPC,blaVIM,blaGES,blaIMP,blaNDM,blaGIM,and blaOXA-23/48 et al.),β-lactamase gene(blaTEM、blaSHV、blaCTX-M),and quinolones resistance gene(qurA,qurB,qurS)were tested by PCR.Plasmid conjugation assay was used to investigate the gene transfer of drug resistance gene.Pulse field gel electrophoresis(PFGE)was used to identify the homology of carbapenems resistance Escherichia coli.Multi-location sequencing test(MLST)was used for numbering of the genes and genotyping of those genes.The genomic affinity assay was tested by Eburst softwares.Results:The carbapenems drug resistance Escherichia coli rate was 5.4%(6/112).Three of them carry blaNDM,one of them carries blaNDM-1,one of them carries blaNDM-3,blaCTX-M-15,and blaTEM-1 genes.The three species that carry blaNDM could successfully transfer the gene to J53 competent cell via plasmid conjugation test.Drug resistance properties were maintained after plasmid transferring,and PCR test confirmed the positive of blaNDM gene.The other three that were not detected drug resistance for carbapenems,one carries bla CTX-M-15 gene,one carries blaTEM-1 gene,the rest carries bla CTX-M-15 gene.Bla KPC,bla VIM,bla GES,bla IMP,bla GIM,bla OXA were not detected.The genes of qurA,qurB,qurS were not detected for those 6 species.Three species that carry blaNDM showed 3 different ST type by MLST assay,namely ST744,ST167,and ST7219.The results from Eburst results,ST744 and ST167 belong to CC10 colony,ST7912 belongs to CC131 clony.PFGE results showed they belong to A,B,and C colony.Conclusions:1.We collected the locate identified carbapenems resitance,which were all multi-drug resistance(MDR)type,but sensitive to Tigecycline and amikacin.Three of them were bla NDM positive Escherichia coli.While the rest three were not detected to be carbapenems resistant.2.First identify the species that carry blaNDM-3 in China,meanwhile,this one also carries blaCTX-M-15,and blaTEM-1 genes.The rest 2 carries blaNDM-1 gene.3.MLST and PFGE results showed no clonal correlation among the three blaNDM positive Escherichia coli.