Identification of a Novel IncHI1B Plasmid in MDR 200 from Swine in China.

Multidrug-resistant (MDR) poses a seriously threat to public health. The aim of this study was to better understand the genetic structure of its plasmids and chromosomes. The whole-genome sequence of 200 isolated from the liver of a swine with diarrhea in China was determined using PacBio RS II and Illumina MiSeq sequencing. The complete sequences of the chromosomal DNA and the plasmids were analyzed for the presence of resistance genes. The phylogenetic trees revealed that 200 displayed the closest relationship to a human-associated strain from Thailand. 200 contained two plasmids, pYhe2001 and pYhe2002, belonging to the incompatibility groups IncH-HI1B and IncF-FIA. The plasmid pYhe2001 was a novel plasmid containing four types of heavy metal resistance genes and a novel Tn transposon flanked by two copies of IS at both ends. Mixed plasmids could be transferred from 200 to DH5α through transformation together. This study reported the first time a novel plasmid pYhe2001 from swine origin 200, suggesting that the plasmids may act as reservoirs for various antimicrobial resistance genes and transport multiple resistance genes in of both animal and human origin.