Two novel Salmonella genomic island 1 variants in Proteus mirabilis isolates from swine farms in China

Four different Salmonella genomic island 1 (SGI1) variants, including two novel variants, were characterized in one Salmonella enterica serovar Rissen sequence type ST1917 isolate and three Proteus mirabilis isolates from swine farms in China. One novel variant was derived from SGI1-B with the backbone gene S021 disrupted by a 12.72-kb IS26 composite transposon containing the dfrA17-aadA5 cassettes and macrolide inactivation gene cluster mphA-mrx-mphR. The other one was an integron-free SGI1 and contained a 183-bp truncated S025 next to IS6100 and S044.