College of Veterinary Medicine, Northwest A&F University, Yangling, China.
Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, China.
Vet Microbiol. 2022 Jun;269:109420. doi: 10.1016/j.vetmic.2022.109420. Epub 2022 Apr 4.
The recent emergence of plasmid-mediated tigecycline resistance gene tet(X) variants represents a threat to public health. tet(X4) is highly endemic in northwestern China. Here, we extended the region to western China to further understand its epidemiology and distribution. During 2018-2020, 1497 faecal samples from pigs, sheep and goats in western China were screened for tet(X4)-positive strains. A total of 134 tigecycline-nonsusceptible Escherichia coli were isolated; among them, the largest number were isolated from Guangxi (66.42%, 89/134), Shaanxi (17.16%, 23/134) and Ningxia (8.21%, 11/134). Antibiotic susceptibility testing showed that all of these isolates were multidrug-resistant bacteria that were also resistant to florfenicol. Eighty-nine of 134 tet(X4)-positive Escherichia coli were analysed by whole-genome sequencing. They belonged to twenty-seven sequence types, and ST10, ST48, ST189 and ST2223 were the main types of Escherichia coli. Seventy-six of the 134 tet(X4)-positive Escherichia coli could transfer tet(X4) into the recipient Escherichia coli 26 R 793. Southern blot analysis showed that there were multiple plasmids carrying the tet(X4) gene in a single strain. The plasmids of the 89 tet(X4)-bearing isolates in this study were analysed. tet(X4)-bearing plasmids ranged from 20 to 400 kb, and the main plasmid types were categorised as IncX1, IncY, and ColRNAI. Guangxi, Ningxia, and Shanxi are likely to be the seminal and most affected areas. Additional efforts are needed to evaluate the impact of the spread of these tigecycline resistance genes and tigecycline-resistant isolates.
最近出现的质粒介导的替加环素耐药基因 tet(X) 变体对公共卫生构成了威胁。tet(X4) 在我国西北地区高度流行。在这里，我们将该区域扩展到中国西部，以进一步了解其流行病学和分布情况。2018-2020 年，从中国西部的猪、羊和山羊中筛选了 1497 份粪便样本，以筛选出 tet(X4)阳性菌株。共分离出 134 株对替加环素不敏感的大肠杆菌；其中，从广西（66.42%，89/134）、陕西（17.16%，23/134）和宁夏（8.21%，11/134）分离出的菌株数量最多。药敏试验结果显示，所有这些分离株均为多重耐药菌，对氟苯尼考也有耐药性。对 134 株 tet(X4)阳性大肠杆菌中的 89 株进行全基因组测序分析。它们属于 27 种序列类型，主要类型为大肠杆菌 ST10、ST48、ST189 和 ST2223。在 134 株 tet(X4)阳性大肠杆菌中，有 76 株可将 tet(X4)转移至受体大肠杆菌 26R793。Southern blot 分析显示，单个菌株中存在多种携带 tet(X4)基因的质粒。分析了本研究中 89 株携带 tet(X4)的分离株的质粒。携带 tet(X4)的质粒大小为 20-400kb，主要质粒类型为 IncX1、IncY 和 ColRNAI。广西、宁夏和山西可能是该基因的起源地和受影响最严重的地区。需要进一步努力评估这些替加环素耐药基因和替加环素耐药分离株传播的影响。
