Resistance mechanism and molecular epidemiology of Escherichia coli producing new delhi metal β-lactamase

Objective To study the molecular typing, drug resistance mechanism and epidemiological characteristics of New Delhi metal β-lactamase (NDM) in Escherichia coli isolated from clinical isolates for prevention and control of nosocomial infections, and provide the basis for treatment. Methods A total of 9 NDM-producing carbapenem-resistant E. coli strains were collected from various clinical samples from June 2017 to February 2018 in the hospital, combined with clinical susceptibility testing, EDTA synergy and synergistic experiments and polymerase chain reaction (PCR) were employed to amplify and detect the blaNDM and other drug resistance gene. Finding out their NDM subtypes through sequence analysis. Analysis of homology among strains by E. coli intergenic consensus polymerase chain reaction (ERIC-PCR) and multiple site typing (MLST). Drug sensitivity experiments, conjugation experiments, PCR amplification and sequence analysis were used to study molecular typing and drug resistance molecular mechanisms of metallo-β-lactamase in E. coli. Results A total of 9 strains of E. coli producing NDM were screened out and form different wards. The NDM subtypes of all the strains were NDM-5 type, and the plasmid replicon types were all IncX3 type. Five strains conjugation test were positive,they were from gynecology, intensive care, emergency and neonatal, and PCR results show that the plasmid replicon type of zygomycetes was also IncX3 type. All the strains showed multidrug resistance. The results of MLST classification showed that there were 4 ST genotypes in 9 NDM-producing E. coli strains, including ST206 type, ST167 type, ST354 type and ST1642 type, which were consistent with ERIC-PCR results. Conclusion The results showed that the presence of E. coli carrying the blaNDM-5 gene in the region presented a certain clonal and clustered fulminant, and it could spread through the IncX3 plasmid in E. coli. In order to prevent and control the outbreak of nosocomial infection, we must pay attention to and strengthen the monitoring of the carbapenem-resistant enterobacteriaceae.