Sun Ruan-Yang, Ke Bi-Xia, Fang Liang-Xing, Guo Wen-Ying, Li Xing-Ping, Yu Yang, Zheng Si-Lin, Jiang Yu-Wei, He Dong-Mei, Sun Jian, Ke Chang-Wen, Liu Ya-Hong, Liao Xiao-Ping
National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, South China Agricultural University, Guangzhou, P. R. China.
Laboratory of Veterinary Pharmacology, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, P. R. China.
J Antimicrob Chemother. 2020 Jul 1;75(7):1756-1765. doi: 10.1093/jac/dkaa115.
To investigate the prevalence and transmission of mcr-3 among Salmonella enterica serotype Typhimurium and 1,4,[5],12:i:-.
A total of 4724 clinical Salmonella isolates were screened for the presence of mcr-3 in China during 2014-19. The clonal relationship of the mcr-3-positive isolates and their plasmid contents and complete sequence were also characterized based on WGS data from the Illumina and MinION platforms.
We identified 10 mcr-3-positive isolates, and all were MDR, mostly resistant to colistin, cefotaxime, ciprofloxacin, doxycycline and florfenicol. mcr-3 was co-present with blaCTX-M-55-qnrS1 on hybrid ST3-IncC-FII conjugatable plasmids (n = 6) and an ST3-IncC non-conjugatable plasmid (n = 1) and embedded into a pCHL5009T-like IncFII plasmid on the Salmonella chromosome (n = 3). Four distinctive genetic contexts surrounded mcr-3 and all but one were closely related to each other and to the corresponding region of IncFII plasmid pCHL5009T. IS15DI was most likely the vehicle for integration of mcr-3-carrying IncFII plasmids into ST3-IncC plasmids and the chromosome and for shaping the MDR regions. In addition, a phylogenetic tree based on the core genome revealed a unique Salmonella lineage (≤665 SNPs) that contained these 10 mcr-3-positive isolates and another 38 (33 from patients) mcr-3-positive Salmonella from five countries. In particular, most of the 51 mcr-3-positive isolates belonged to ST34 and harboured diverse antibiotic resistance genes (ARGs), including mcr-3-blaCTX-M-55-qnrS1, and possessed similar ARG profiles.
Our findings revealed global clonal spread of MDR ST34 Salmonella from clinical isolates co-harbouring mcr-3 with blaCTX-M-55 and qnrS1 and a flexibility of mcr-3 co-transmittance with other ARGs mediated by mobile genetic elements.
调查鼠伤寒沙门氏菌和1,4,[5],12:i: -血清型中mcr - 3的流行情况及传播情况。
2014 - 2019年期间，在中国对总共4724株临床沙门氏菌分离株进行了mcr - 3检测。基于Illumina和MinION平台的全基因组测序（WGS）数据，对mcr - 3阳性分离株的克隆关系、质粒内容物和完整序列也进行了特征分析。
我们鉴定出10株mcr - 3阳性分离株，均为多重耐药（MDR），大多对黏菌素、头孢噻肟、环丙沙星、强力霉素和氟苯尼考耐药。mcr - 3与blaCTX - M - 55 - qnrS1共存于杂交ST3 - IncC - FII可接合质粒（n = 6）和一个ST3 - IncC非可接合质粒（n = 1）上，并嵌入沙门氏菌染色体上的一个类似pCHL5009T的IncFII质粒中（n = 3）。mcr - 3周围有四种不同的基因背景，除一个外，其余所有背景彼此密切相关，且与IncFII质粒pCHL5009T的相应区域相关。IS15DI最有可能是携带mcr - 3的IncFII质粒整合到ST3 - IncC质粒和染色体中以及塑造多重耐药区域的载体。此外，基于核心基因组的系统发育树揭示了一个独特的沙门氏菌谱系（≤665个单核苷酸多态性），其中包含这10株mcr - 3阳性分离株以及来自五个国家的另外38株（33株来自患者）mcr - 3阳性沙门氏菌。特别是，51株mcr - 3阳性分离株中的大多数属于ST34，携带多种抗生素耐药基因（ARGs），包括mcr - 3 - blaCTX - M - 55 - qnrS1，并且具有相似的ARG谱。
我们的研究结果揭示了携带mcr - 3与blaCTX - M - 55和qnrS1的临床分离多重耐药ST34沙门氏菌的全球克隆传播，以及mcr - 3与其他由移动遗传元件介导的ARGs共传播的灵活性。
