Molecular Genetic Characteristics of Plasmid-Borne in Serotype Typhimurium and Thompson in Zhejiang, China.

is a zoonotic food-borne pathogen threatening public health around the world. As is the case with many other pathogens, the spread of mobilized colistin resistance () alleles is of grave concern. In this study, totally 689 clinical isolates were collected from a local hospital in Hangzhou, Zhejiang Province, China between 2009 and 2018. Resistance genes were screen by PCR. Two positive strains S15 and S639 were identified which belong to serotype Typhimurium and Thompson, respectively. We observed that both genes were located on conjugative IncHI2 plasmids which encoded numerous resistance genes, likely facilitating the dissemination of by co-resistance mechanisms. The cassettes encoded on the two plasmids were not identical: downstream of the genes, we found IS on one plasmid (pS15), while the other had a -IS (pS639). Despite the presence of cassettes, the strains were not rendered colistin resistant. Yet, it is of epidemiological importance to implement surveillance to be able to observe and possibly control the spread of due to its potential to mediate resistance to the last-resort antibiotic colistin.