Plasmid Dynamics of -Positive spp. in a General Hospital in China.

is an important food pathogen that can cause severe gastroenteritis with more than 600,000 deaths globally every year. Colistin (COL), a last-resort antibiotic, is ineffective in bacteria that carry a functional gene, which is often spread by conjugative plasmids. Our work aimed to understand the prevalence of the gene in clinical isolates of , as the frequency of occurrence of the gene is increasing globally. Therefore, we analyzed 689 clinical strains, that were isolated between 2009 and late 2018. The gene was found in six strains, which we analyzed in detail by whole genome sequencing and antibiotic susceptibility testing, while we also provide the clinical information on the patients suffering from an infection. The genomic analysis revealed that five strains had plasmid-encoded gene located in four IncHI2 plasmids and one IncI2 plasmid, while one strain had the chromosomal gene originated from plasmid. Surprisingly, in two strains the genes were inactive due to disruption by insertion sequences (ISs): IS and IS. A detailed analysis of the plasmids revealed a multitude of ISs, most commonly IS. The IS contained genes that meditate broad resistance toward most antibiotics underlining their importance of the mobile elements, also with respect to the spread of the gene. Our study revealed potential reservoirs for the transmission of COL resistance and offers insights into the evolution of the gene in .