State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-Products, Institute of Agro-product Safety and Nutrition, Zhejiang Academy of Agricultural Sciences, Hangzhou, China.
International Joint Research Center of National Animal Immunology, College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, China.
Microbiol Spectr. 2023 Jun 15;11(3):e0274122. doi: 10.1128/spectrum.02741-22. Epub 2023 Mar 30.
The aim of this study was to investigate the transferability of acquired linezolid resistance genes and associated mobile genetic elements in an Enterococcus faecalis isolate QZ076, cocarrying , , (D), and genes. MICs were determined by broth microdilution. Whole-genome sequencing (WGS) was performed using the Illumina and Nanopore platforms. The transfer of linezolid resistance genes was investigated by conjugation, using E. faecalis JH2-2 and clinical methicillin-resistant Staphylococcus aureus (MRSA) 109 as recipients. E. faecalis QZ076 harbors four plasmids, designated pQZ076-1 to pQZ076-4, with located in the chromosomal DNA. The gene was located on a novel pseudocompound transposon, designated Tn, integrated into the 65,961-bp pCF10-like pheromone-responsive conjugative plasmid pQZ076-1. Tn generated 8-bp direct target duplications (5'-GATACGTA-3'). The genes (D) and were colocated on the 16,397-bp mobilizable broad-host-range Inc18 plasmid pQZ076-4. The -carrying plasmid pQZ076-1 could transfer from E. faecalis QZ076 to E. faecalis JH2-2, along with the (D)- and -cocarrying plasmid pQZ076-4, conferring the corresponding resistant phenotype to the recipient. Moreover, pQZ076-4 could also transfer to MRSA 109. To the best of our knowledge, this study presented the first report of four acquired linezolid resistance genes [, , (D), and ] being simultaneously present in the same E. faecalis isolate. The location of the gene on a pseudocompound transposon in a pheromone-responsive conjugative plasmid will accelerate its rapid dissemination. In addition, the -carrying pheromone-responsive conjugative plasmid in E. faecalis was also able to mobilize the interspecies transfer of the (D)- and -cocarrying plasmid between enterococci and staphylococci. In this study, the simultaneous occurrence of four acquired oxazolidinone resistance genes [, , (D), and ] was identified in an E. faecalis isolate of chicken origin. The association of the gene with a novel pseudocompound transposon Tn integrated into a pCF10-like pheromone-responsive conjugative plasmid will accelerate its dissemination. Moreover, the location of the resistance genes (D) and on a mobilizable broad-host-range Inc18 family plasmid represents the basis for their intra- and interspecies dissemination with the aid of a conjugative plasmid and further accelerates the spreading of acquired oxazolidinone resistance genes, such as , (D), and , among Gram-positive pathogens.
本研究旨在调查屎肠球菌分离株 QZ076 中携带的获得性利奈唑胺耐药基因和相关移动遗传元件的可转移性，该分离株同时携带、、（D）和 基因。采用肉汤微量稀释法测定 MIC。使用 Illumina 和 Nanopore 平台进行全基因组测序（WGS）。通过接合实验研究利奈唑胺耐药基因的转移，使用屎肠球菌 JH2-2 和临床耐甲氧西林金黄色葡萄球菌（MRSA）109 作为受体。屎肠球菌 QZ076 携带四个质粒，分别命名为 pQZ076-1 至 pQZ076-4， 基因位于染色体 DNA 中。基因 位于一个新的假复合转座子 Tn 上，该转座子整合到 65961bp 的 pCF10 样性导型可接合质粒 pQZ076-1 中。Tn 产生了 8bp 的直接靶标重复（5'-GATACGTA-3'）。基因（D）和 位于可移动的广泛宿主范围 Inc18 质粒 pQZ076-4 的 16397bp 可移动元件上。携带 的质粒 pQZ076-1 可以从屎肠球菌 QZ076 转移到屎肠球菌 JH2-2，同时携带（D）和 -共携带的质粒 pQZ076-4，赋予受体相应的耐药表型。此外，pQZ076-4 也可以转移到 MRSA 109。据我们所知，本研究首次报道了在同一屎肠球菌分离株中同时存在四个获得性利奈唑胺耐药基因 [、、（D）和 ]。基因位于性导型可接合质粒上的假复合转座子上，将加速其快速传播。此外，屎肠球菌中的携带 基因的性导型可接合质粒也能够促进（D）和 -共携带的质粒在肠球菌和葡萄球菌之间的种间转移。在本研究中，在鸡源屎肠球菌分离株中鉴定出四个获得性唑烷酮类耐药基因 [、、（D）和 ] 的同时发生。基因与新型假复合转座子 Tn 相关联，该转座子整合到 pCF10 样性导型可接合质粒中，将加速其传播。此外，耐药基因（D）和 位于可移动的广泛宿主范围 Inc18 家族质粒上，这是它们在种内和种间传播的基础，借助接合质粒进一步加速获得性唑烷酮类耐药基因（如、（D）和 ）在革兰氏阳性病原体中的传播。
