Characteristics of Plasmids Coharboring 16S rRNA Methylases, CTX-M, and Virulence Factors in Escherichia coli and Klebsiella pneumoniae Isolates from Chickens in China

Abstract The objective of this study was to characterize plasmids coharboring 16S rRNA methylases, blaCTX-M and virulence-associated genes in Escherichia coli and Klebsiella pneumoniae isolates from chickens in China. A total of 32 positive transconjugants exhibited coresistance to amikacin and cefotaxime in E. coli (24/281) and K. pneumoniae (8/93), and were identified by conjugation experiments and S1-pulsed-field gel electrophoresis. Polymerase chain reaction amplification assay detecting resistance genes showed that rmtB or armA gene accompanied with different blaCTX-M genes coexisted on 32 transferred plasmids. The blaCTX-M-98b gene was identified in chicken-derived E. coli and K. pneumoniae for the first time. The association between resistance genes and virulence genes was observed in the transferred plasmids; 68.8% (22/32) transferred resistance plasmids coharboring various virulence genes including traT, iutA, fyuA, msbB, and vagC genes with diverse proportions. Genetic stability tests revealed t...