Characteristics and blaNDM-1 genetic environment of plasmid from Enterobacter aerogenes

Abstract:

ObjectiveTo study plasmidmediated transfer, plasmid replicon typing, and genetic environment of blaNDM1 gene in Enterobacter aerogenes(E. aerogenes).MethodsE. aerogenes HNNDM0711 was used as the subject of this research, the transferable properties of plasmid were analyzed by conjugation testing, conjugant was performed stability testing, plasmid type was determined by PCRbased replicon typing (PBRT), downstream and upstream of blaNDM1 were sequenced using chromosome walking method, genetic context was analyzed by BLASTN and BALSTP, as well as annotated using Vector NTI 11.5.1 software, sequence pipeline graph was made, the sequence was submitted to Genbank through software Banklt.ResultsThe conjugation testing of E. aerogenes pHNNDM0711 was positive, after positive conjugant was conducted 4day passage, minimal inhibitory concentrations (MICs) of imipenem and meropenem to all the cloned strains didn’t change, blaNDM1 were all positive. The replicon type was IncA/C; blaNDM1 gene was localized between ISAba14 and IS91, at upstream of the blaNDM1, class 1 integron and Tn3 transposon were identified, class 1 integron contained a new mosaic structure of a drugresistant resistance gene cassette.ConclusionE. aerogenes pHNNDM0711, bearing blaNDM1 gene in IncA/C plasmid, derived from gene recombination under different antimicrobial selection pressure. Antimicrobial use in clinical, industrial and agricultural area should be strictly controlled, so as to reduce the emergence of such bacteria.