title: Characterization of an rmtB-carrying IncI1 ST136 plasmid in avian Escherichia coli isolates from chickens.
abstract: The rmtB gene, one of the 16S rRNA methylase genes whose products confer high-level resistance to aminoglycosides, is most prevalent among Enterobacteriaceae strains. In this study, eight non-duplicate rmtB-carrying avian Escherichia coli strains from a farm in China were isolated and characterized, and further examined by phylogenetic grouping, conjugation experiments and PCR-based replicon typing. In addition, the genetic environment of rmtB was investigated by cloning and sequencing. Six rmtB-carrying E. coli were identified as phylogroup A, sequence type (ST) 156 (A-ST156), with two assigned to D-ST117; however, all of them carried the same IncI1 ST136 plasmid. The genetic environment of the rmtB gene in these eight plasmids was the same, as shown by PCR mapping. A multidrug-resistant region carrying blaTEM-1, rmtB, a class 1 integron cassette array (intI1-dfrA12-orfF-aadA2-qacEΔ1-sul1) and aacC2 was characterized on the conjugative IncI1 ST136 plasmid. Co-location of the rmtB gene with a class 1 integron cassette array and aacC2 on the conjugative plasmid will facilitate its maintenance and dissemination.
authors.affiliation: College of Animal Science and Veterinary Medicine, Henan Agricultural University,Zhengzhou 450002,PR China.
authors.forename: Tong
authors.initials: T
authors.lastname: Fu
authors.affiliation: College of Animal Science and Veterinary Medicine, Henan Agricultural University,Zhengzhou 450002,PR China.
authors.forename: Xiang-Dang
authors.initials: XD
authors.lastname: Du
authors.affiliation: College of Animal Science and Veterinary Medicine, Henan Agricultural University,Zhengzhou 450002,PR China.
authors.forename: Pei-Pei
authors.initials: PP
authors.lastname: Cheng
authors.affiliation: College of Animal Science and Veterinary Medicine, Henan Agricultural University,Zhengzhou 450002,PR China.
authors.forename: Xiao-Ran
authors.initials: XR
authors.lastname: Li
authors.affiliation: College of Animal Science and Veterinary Medicine, Henan Agricultural University,Zhengzhou 450002,PR China.
authors.forename: Xin-Fang
authors.initials: XF
authors.lastname: Zhao
authors.affiliation: College of Animal Science and Veterinary Medicine, Henan Agricultural University,Zhengzhou 450002,PR China.
authors.forename: Yu-Shan
authors.initials: YS
authors.lastname: Pan