Antimicrobial Resistance and Genomic Characterization of Two mcr-1-Harboring Foodborne Salmonella Isolates Recovered in China, 2016

The mcr-1 gene mediating mobile colistin resistance in Escherichia coli was first reported China 2016 followed by reports among different species worldwide, especially E. and Klebsiella . However, data on its transmission Salmonella are still lacking. This study analyzed the antimicrobial (AMR) profiles presence 755 foodborne from 26 provinces of mainland, 2016. Genomic features two mcr-1- carrying isolates, genome sequencing, serotypes further were studied. Among tested, 72.6% found to be resistant at least one agent 10% defined as multi-drug (MDR). Derby CFSA231 Typhimurium CFSA629 -harboring isolates. Both expressed an MDR phenotype included a single circular chromosome plasmid. 22 AMR genes identified S CFSA231, only localized IncX4 type plasmid pCFSA231 while 20 chromosomal genes, including four plasmid-mediated quinolone (PMQR) mapped within 64 kb genomic island (SGI) like region. possessed 11 mcr-1.19 variant ESBL genes. Two IS -flanked composite-like transposons identified. Additionally, 153 152 virulence factors separately these isolates with secretion system fimbrial adherence determinants dominant classes. Our extends our concern -carrying regards factors, highlight importance surveillance mitigate dissemination mcr -encoding