Ma Zhenbao, Liu Jiao, Chen Lin, Liu Xiaoqin, Xiong Wenguang, Liu Jian-Hua, Zeng Zhenling
Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural University, Guangzhou 510642, China.
National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China.
Pathogens. 2021 Jan 3;10(1):33. doi: 10.3390/pathogens10010033.
This paper aimed to investigate the molecular epidemiological features of the gene in isolates in a typical swine farm during 2014-2017. A total of 617 isolates were screened for the gene using PCR amplification. A susceptibility test, pulsed-field gel electrophoresis (PFGE), S1-PFGE, southern blotting hybridization, and the genetic context of the gene were all used for analyzing all -positive isolates. A conjugation experiment was conducted with the broth mating method using C600 as the recipient strain and 45 -bearing isolates as the donor strain. Plasmids pHNEP124 and pHNEP129 were revealed by Illumina Miseq 2500. Eighty-five (13.7%) isolates were positive for the gene and the prevalence of the gene had significantly increased from 1.6% in 2014 to 29.1% in 2017. The Pulsed-Field Gel Electrophoresis (PFGE) analysis indicated that the spread of the gene among isolates was mainly due to horizontal transfer. In addition, the gene was primarily located on the plasmids between 28.8-kb to 60-kb in size, and the gene was flanked by two copies of IS with the same orientation. Sequence analysis suggested that the plasmids pHNEP124 and pHNEP129 co-harboring the and genes belonged to the plasmids IncP plasmid and IncX4 plasmid, respectively. In conclusion, this is the first study to report the high prevalence of the gene among isolates and the first report of the complete genome sequence of IncP and IncX4 plasmids carrying the and genes. The occurrence and dissemination of the -carrying plasmids among isolates need further surveillance.
本文旨在调查2014 - 2017年期间一个典型养猪场分离株中该基因的分子流行病学特征。使用PCR扩增对总共617株分离株进行该基因筛查。对所有该基因阳性的分离株进行药敏试验、脉冲场凝胶电泳（PFGE）、S1 - PFGE、Southern印迹杂交以及该基因的遗传背景分析。以C600作为受体菌株，45株携带该基因的分离株作为供体菌株，采用肉汤交配法进行接合实验。通过Illumina Miseq 2500揭示了质粒pHNEP124和pHNEP129。85株（13.7%）分离株该基因呈阳性，该基因的流行率从2014年的1.6%显著增加到2017年的29.1%。脉冲场凝胶电泳（PFGE）分析表明该基因在分离株中的传播主要是由于水平转移。此外，该基因主要位于大小在28.8 - kb至60 - kb之间的质粒上，且该基因两侧有两个同向的IS拷贝。序列分析表明，共同携带该基因和另一基因的质粒pHNEP124和pHNEP129分别属于IncP质粒和IncX4质粒。总之，这是首次报道该基因在分离株中高流行率的研究，也是首次报道携带该基因和另一基因的IncP和IncX4质粒的全基因组序列。携带该基因的质粒在分离株中的出现和传播需要进一步监测。
