Wang Xiaoming, Ling Zhuoren, Sun Naiyan, Liu Yongshi, Huang Jinhu, Wang Liping
MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.
Beijing Advanced Innovation Centre for Food Nutrition and Human Health, College of Veterinary Medicine, China Agricultural University, Beijing, China.
Int J Antimicrob Agents. 2021 May;57(5):106332. doi: 10.1016/j.ijantimicag.2021.106332. Epub 2021 Mar 30.
Among the 10 reported mcr genes, mcr-9 was first identified in Salmonella enterica serotype Typhimurium, which is a leading cause of foodborne illness worldwide. However, information about the prevalence and genetic features of mcr-9 is still lacking, especially among food samples. This study reports the presence of mcr-9 in raw milk samples from China; the prevalence rate was low (0.83%, 1/120). mcr-9 was located on a transferable plasmid, and was stable in wild-type S. enterica. However, it had a biological fitness cost when transferred to an Escherichia coli recipient. Whole-genome sequencing revealed that mcr-9 was located on the IncHI2A-type plasmid, and was surrounded by IS903B and IS26 in its flanking regions. The mcr-9-carrying S. enterica 19SE belonged to ST26 and had a multi-drug-resistant phenotype. It was confirmed that mcr-9 did not mediate colistin resistance in this study, indicating that its transfer may not facilitate the dissemination of colistin resistance.
在已报道的10种mcr基因中，mcr - 9首次在肠炎沙门氏菌鼠伤寒血清型中被鉴定出来，该血清型是全球食源性疾病的主要病因。然而，关于mcr - 9的流行情况和基因特征的信息仍然匮乏，尤其是在食品样本中。本研究报告了中国生乳样本中存在mcr - 9；其流行率较低（0.83%，1/120）。mcr - 9位于一个可转移质粒上，在野生型肠炎沙门氏菌中稳定存在。然而，当它转移到大肠杆菌受体菌时具有生物学适应性代价。全基因组测序显示，mcr - 9位于IncHI2A类型质粒上，其侧翼区域被IS903B和IS26包围。携带mcr - 9的肠炎沙门氏菌19SE属于ST26，具有多重耐药表型。本研究证实mcr - 9在本研究中不介导黏菌素耐药性，这表明其转移可能不会促进黏菌素耐药性的传播。
