Characterization of pHeBE7, an IncFII-type virulence-resistance plasmid carrying bla, blaand rmtB genes, detected in Escherichia coli from a chicken isolate in China.

Abstract

Recently, a novel variant of the CTX-M enzyme, CTX-M-98, was detected in Escherichia coli isolates from food animals. However, few plasmids carrying blahave been fully characterized. In this study, we sequenced the complete pHeBE7 plasmid, an 86,015-bp plasmid that contains the bla, bla, rmtB, and traT genes, using whole-genome sequencing. The backbone of pHeBE7 shows a high similarity (>99%) to pMC-NDM, which carries the blagene, however its mosaic regions remain relatively unique among sequenced plasmids. We discovered that a typical ISEcp1-bla-IS903 element in the mosaic region harbors the blagene. Conjugation and growth competition assays indicate that pHeBE7 can be easily transmitted and that it confers a limited fitness cost to the recipient cell. The genetic characterization of pHeBE7 may improve our knowledge of how antibiotic resistance disseminates in enterobacteria.