Short communication: Whole-genome sequence analysis of 4 fecal bla_(CMY-2）-producing Escherichia coli isolates from Holstein dairy calves

摘要

This study was carried out to determine the antimicrobialresistance (AMR) genes and mobile geneticelements of 4 fecal blaCMY-2-producing Escherichia coliisolated from Holstein dairy calves on the same farmusing whole-genome sequencing. Genomic analysis revealedthat 3 of the 4 isolates shared similar geneticfeatures, including sequence type (ST), serotype, plasmidcharacteristics, insertion ST, and virulence genes.In addition to genes encoding for complex multidrugresistance efflux systems, all 4 isolates were carriersof genes conferring resistance to β-lactams (blaCMY-2,bla_(TEM-1B)), tetracyclines (tetA, tetB, tetD), aminoglycosides[aadA1, aph(3")-lb, aph(6)-ld], sulfonamides(sul2), and trimethoprim (dfrA1). We also detected 4incompatibility plasmid groups: Inc.F, Inc.N, Inc.I, andInc.Q. A novel ST showing a new purA and mdh alleliccombination was found. The 4 isolates were likelyenterotoxigenic pathotypes of E. coli, based on serotypeand presence of the plasmid Inc.FII(pCoo). This studyprovides information for comparative genomic analysisof AMR genes and mobile genetic elements. Thisanalysis could give some explanation to the multidrugresistance characteristics of bacteria colonizing the intestinaltract of dairy calves in the first few weeks oflife.