College of Veterinary Medicine, Northwest A&F University, Yangling, China.
College of Food Science and Engineering, Northwest A&F University, Yangling, China.
Front Cell Infect Microbiol. 2020 Dec 10;10:586507. doi: 10.3389/fcimb.2020.586507. eCollection 2020.
Tigecycline is the antibiotic of last resort for the treatment of extensively drug-resistant bacterial infections, mainly those of multidrug-resistant Gram-negative bacteria. The plasmid-mediated (X3) gene has recently been described in various pathogens that are resistant to tigecycline. We report three tigecycline-resistant strains isolated from porcine faeces in China, which all contained the (X3)-harboring plasmids. A broth microdilution method was used to examine the antimicrobial susceptibility of the isolates, and S1-Nuclease digestion pulsed-field gel electrophoresis (S1-PFGE) was used to characterize their plasmid profiles. The whole-genome sequences of the isolates were determined with the Nanopore PromethION platform. The sequence analysis indicated that the strains were They showed resistance to multiple antibiotics, and all the resistance genes were located on plasmids. The three (X3)-harboring plasmids had a similar backbone structure, and all contained with various insertion elements (IS). IS is considered an important factor in (X3) mobilization. In addition to IS, we demonstrate that IS generates a circular intermediate containing the (X3) gene, which could increase the dissemination risk. To our knowledge, this is the first report of (X3)- and -harboring plasmids in . Because the IS is frequently found in front of (X3), research should be directed toward the action of IS in the spread of (X3).
替加环素是治疗广泛耐药细菌感染的最后手段抗生素，主要针对多药耐药革兰氏阴性菌。质粒介导的（X3）基因最近在各种对替加环素耐药的病原体中被描述。我们报告了三株从中国猪粪便中分离出的对替加环素耐药的菌株，它们都含有（X3）携带的质粒。采用肉汤微量稀释法检测分离株的抗菌药敏性，采用 S1-核酸酶消化脉冲场凝胶电泳（S1-PFGE）分析其质粒图谱。采用 Nanopore PromethION 平台对分离株的全基因组序列进行测定。序列分析表明，这些菌株属于，它们对多种抗生素表现出耐药性，所有耐药基因都位于质粒上。三个（X3）携带的质粒具有相似的骨架结构，都包含了不同的插入元件（IS）。IS 被认为是（X3）移动的重要因素。除了 IS，我们还证明 IS 产生了一个包含（X3）基因的环状中间产物，这可能会增加传播风险。据我们所知，这是首次在报道（X3）和 -携带质粒。由于 IS 经常出现在（X3）前面，因此应该研究 IS 在（X3）传播中的作用。
