biostudies-literatureUnknown13Fan J<i>Salmonella enterica</i> 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 (<i>mcr</i>) alleles is of grave concern. In this study, totally 689 clinical <i>Salmonella</i> isolates were collected from a local hospital in Hangzhou, Zhejiang Province, China between 2009 and 2018. Resistance genes were screen by PCR. Two <i>mcr-9-</i>positive <i>Salmonella</i> strains S15 and S639 were identified which belong to serotype Typhimurium and Thompson, respectively. We observed that both <i>mcr-9</i> genes were located on conjugative IncHI2 plasmids which encoded numerous resistance genes, likely facilitating the dissemination of <i>mcr-9</i> by co-resistance mechanisms. The <i>mcr-9</i> cassettes encoded on the two plasmids were not identical: downstream of the <i>mcr-9</i> genes, we found IS<i>1</i> on one plasmid (pS15), while the other had a <i>WbuC</i>-IS<i>26</i> (pS639). Despite the presence of <i>mcr-9</i> 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 <i>mcr-9</i> due to its potential to mediate resistance to the last-resort antibiotic colistin.Frontiers in microbiology852434https://www.ebi.ac.uk/biostudies/studies/S-EPMC8969412biostudies-literatureMolecular Genetic Characteristics of Plasmid-Borne <i>mcr-9</i> in <i>Salmonella enterica</i> Serotype Typhimurium and Thompson in Zhejiang, China.PMC8969412Fang YHua XYang YFan JHe JXu QLeptihn SZhang LZhao DCai HYu YfalseMolecular Genetic Characteristics of Plasmid-Borne <i>mcr-9</i> in <i>Salmonella enterica</i> Serotype Typhimurium and Thompson in Zhejiang, China.<i>Salmonella enterica</i> 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 (<i>mcr</i>) alleles is of grave concern. In this study, totally 689 clinical <i>Salmonella</i> isolates were collected from a local hospital in Hangzhou, Zhejiang Province, China between 2009 and 2018. Resistance genes were screen by PCR. Two <i>mcr-9-</i>positive <i>Salmonella</i> strains S15 and S639 were identified which belong to serotype Typhimurium and Thompson, respectively. We observed that both <i>mcr-9</i> genes were located on conjugative IncHI2 plasmids which encoded numerous resistance genes, likely facilitating the dissemination of <i>mcr-9</i> by co-resistance mechanisms. The <i>mcr-9</i> cassettes encoded on the two plasmids were not identical: downstream of the <i>mcr-9</i> genes, we found IS<i>1</i> on one plasmid (pS15), while the other had a <i>WbuC</i>-IS<i>26</i> (pS639). Despite the presence of <i>mcr-9</i> 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 <i>mcr-9</i> due to its potential to mediate resistance to the last-resort antibiotic colistin.2022-01-01T00:00:00Z20222024-11-12T10:49:47.327Z2024-11-12T10:49:47.327ZS-EPMC89694123536945910.3389/fmicb.2022.852434