Zhao Yongda, Guo Lili, Li Jie, Huang Xianhui, Fang Binghu
College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong, China.
Qingdao Yebio Biological Engineering Co., Ltd, Qingdao, Shandong, China.
PeerJ. 2018 Apr 9;6:e4613. doi: 10.7717/peerj.4613. eCollection 2018.
is a common porcine respiratory pathogen that causes high rates of morbidity and mortality in farmed swine. We performed a molecular characterization of antimicrobial resistance genes harbored by from pig farms in China.
We screened 143 isolates for antimicrobial susceptibility against six fluoroquinolone antibiotics testing by the broth microdilution method, and the presence of 64 antimicrobial resistance genes by PCR amplification and DNA sequence analysis. We determined quinolone resistance determining region mutations of DNA gyrase ( and ) and topoisomerase IV ( and ). The genetic relatedness among the strains was analyzed by pulsed-field gel electrophoresis.
Susceptibility test showed that all isolates were low resistance to lomefloxacin (28.67%), levofloxacin (20.28%), norfloxacin (22.38%), ciprofloxacin (23.78%), however, high resistance levels were found to nalidixic acid (82.52%) and enrofloxacin (55.94%). In addition, we found 14 antimicrobial resistance genes were present in these isolates, including , genes. Interestingly, one isolate carried five antibiotic resistance genes (). The genes , and were the most prevalent resistance genes in in China. Alterations in the gene (S83F/Y, D87Y/N/H/G) were detected in 81% of the strains and mutations were often accompanied by a mutation. Pulsed-field gel electrophoresis typing revealed 51 unique patterns in the isolates carrying high-level antibiotic resistance genes, indicating considerable genetic diversity and suggesting that the genes were spread horizontally.
The current study demonstrated that the high antibiotic resistance of in piglets is a combination of transferable antibiotic resistance genes and multiple target gene mutations. These data provide novel insights for the better understanding of the prevalence and epidemiology of antimicrobial resistance in .
[病原体名称]是一种常见的猪呼吸道病原体，可导致养殖猪的高发病率和死亡率。我们对来自中国猪场的[病原体名称]携带的抗菌药物耐药基因进行了分子特征分析。
我们通过肉汤微量稀释法对143株[病原体名称]分离株进行了六种氟喹诺酮类抗生素的药敏试验，并通过PCR扩增和DNA序列分析检测了64种抗菌药物耐药基因的存在。我们确定了DNA旋转酶（[基因名称1]和[基因名称2]）和拓扑异构酶IV（[基因名称3]和[基因名称4]）的喹诺酮耐药决定区突变。通过脉冲场凝胶电泳分析菌株之间的遗传相关性。
药敏试验表明，所有分离株对洛美沙星（28.67%）、左氧氟沙星（20.28%）、诺氟沙星（22.38%）、环丙沙星（23.78%）的耐药性较低，然而，对萘啶酸（82.52%）和恩诺沙星（55.94%）的耐药水平较高。此外，我们发现这些分离株中存在14种抗菌药物耐药基因，包括[基因名称5]、[基因名称6]基因。有趣的是，一株分离株携带了五个抗生素耐药基因（[基因名称7]）。[基因名称5]、[基因名称6]和[基因名称7]基因是中国[病原体名称]中最普遍的耐药基因。在81%的菌株中检测到[基因名称8]基因（S83F/Y、D87Y/N/H/G）的改变，并且[基因名称8]突变通常伴随着[基因名称9]突变。脉冲场凝胶电泳分型显示，携带高水平抗生素耐药基因的分离株中有51种独特模式，表明存在相当大的遗传多样性，并表明这些基因是水平传播的。
当前研究表明，仔猪中[病原体名称]的高抗生素耐药性是可转移的抗生素耐药基因和多个靶基因突变共同作用的结果。这些数据为更好地了解[病原体名称]中抗菌药物耐药性的流行情况和流行病学提供了新的见解。
