College of Veterinary Medicine, Key Laboratory of Zoonosis of Ministry of Agricultural and Rural Affairs, National Risk Assessment Laboratory for Antimicrobial Resistance of Microorganisms in Animals, Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou, China.
Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China.
Antimicrob Agents Chemother. 2021 Mar 18;65(4). doi: 10.1128/AAC.02229-20.
We recently identified a novel plasmid-mediated resistance-nodulation-division (RND)-type efflux pump gene cluster, , in that conferred resistance to multiple antimicrobials, including tigecycline. While homologs of were found encoded in many other bacterial species in GenBank, their functions and transfer mechanisms remain unknown. This study identified another mobile gene cluster, , co-occurring on both a plasmid (pHNNC189-2) and the chromosome of a clinical isolate, strain NC189, producing KPC-2, NDM-1, and RmtC. shares high similarity at the nucleotide level with , with 98.02%, 96.75%, and 99.93% identities to , , and , respectively. Phylogenetic analysis revealed that may have originated from the chromosome of a species. The expression of in an strain resulted in an 8-fold increase in the tigecycline MIC and decreased susceptibility to other antimicrobials. Genetic context analyses demonstrated that , together with the adjacent hypothetical site-specific integrase genes, was possibly captured and mobilized by a XerD-like tyrosine recombinase system, forming a putative transposition unit (-like--like-Δ--like--like-ISΔ), which was inserted into like genes in both the NC189 plasmid pHNNC189-2 and the chromosome. Since and could confer multidrug resistance, the spread of these gene clusters, associated with the new recombinase system, calls for more attention.
我们最近在 中发现了一个新型的质粒介导的耐药性-结节-分裂（RND）型外排泵基因簇 ，该基因簇赋予了对多种抗菌药物的耐药性，包括替加环素。虽然在 GenBank 中发现了许多其他细菌物种中编码的 的同源物，但它们的功能和转移机制仍然未知。本研究鉴定了另一个移动基因簇 ，它同时存在于质粒 (pHNNC189-2) 和临床 分离株 NC189 的染色体上，该分离株产生 KPC-2、NDM-1 和 RmtC。在核苷酸水平上， 与 高度相似，与 、 和 的同源性分别为 98.02%、96.75%和 99.93%。系统发育分析表明， 可能起源于 物种的染色体。在 菌株中表达 导致替加环素 MIC 增加 8 倍，并降低对其他抗菌药物的敏感性。遗传背景分析表明， 与相邻的假定位点特异性整合酶基因一起，可能被 XerD 样酪氨酸重组酶系统捕获和移动，形成一个假定的转位单元 (-like--like-Δ--like--like-ISΔ)，该单元插入到 NC189 质粒 pHNNC189-2 和染色体中的 样基因中。由于 和 可以赋予多药耐药性，因此与新重组酶系统相关的这些基因簇的传播需要引起更多关注。
