摘要

背景：水产养殖在世界范围内呈上升趋势，抗生素的使用正在促进更高的生产强度。 然而，最近的研究结果表明抗生素的使用是以增加抗生素耐药性为代价的。 而且，口服抗生素对鱼肠中微生物抗性基因的移动性的影响尚不清楚。 在本研究中，Piaratus mesopotamicus被用作模型来评估抗微生物氟苯尼考对使用宏基因组方法的肠道微生物组以及抗生素抗性基因（ARG）和可移动的遗传元件（MGE）多样性的影响。

结果：
在抗生素暴露期间，ARG和MGE的总相对丰度显着增加。 另外，由于抗生素暴露，噬菌体整合酶，转座酶和侧翼ARG的转座子在P. mesopotamicus的肠道微生物组中积累。 与ARG共同发生的MGE显示与发现的总ARGs呈正相关。 此外，在氟苯尼考处理后，观察到肠道微生物组向着名的假定病原体如沙门氏菌，Plesiomonas和柠檬酸杆菌的转变。 主要是Plesiomonas和Citrobacter携带编码多药和苯酚外排泵的基因。 此外，由于抗生素应用，与RNA加工和修饰，细胞运动，SOS反应和细胞外结构相关的几个基因被富集。 观察到的效果在整个施用阶段是可见的，并且在暴露后阶段消失。

结论：

我们的研究结果表明，口服抗生素增加了MGE介导的鱼类肠道内ARGs交换的可能性，并有助于ARGs在水产养殖系统中的富集和分散。 重要的是，ARG交换潜力的增加可能是社区结构和/或ARG动员变化的结果。
Abstract
BACKGROUND:
Aquaculture is on the rise worldwide, and the use of antibiotics is fostering higher production intensity. However, recent findings suggest that the use of antibiotics comes at the price of increased antibiotic resistance. Yet, the effect of the oral administration of antibiotics on the mobility of microbial resistance genes in the fish gut is not well understood. In the present study, Piaractus mesopotamicus was used as a model to evaluate the effect of the antimicrobial florfenicol on the diversity of the gut microbiome as well as antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) using a metagenomic approach.

RESULTS:
The total relative abundance of ARGs and MGEs significantly increased during the antibiotic exposure. Additionally, phage integrases, transposases, and transposons flanking ARGs accumulated in the gut microbiome of P. mesopotamicus because of the antibiotic exposure. MGEs co-occurring with ARGs showed a significant positive correlation with the total ARGs found. Furthermore, shifts in the gut microbiome towards well-known putative pathogens such as Salmonella, Plesiomonas, and Citrobacter were observed following florfenicol treatment. Mainly Plesiomonas and Citrobacter harbored genes that code for multidrug and phenicol efflux pumps. Moreover, several genes related to RNA processing and modification, cell motility, SOS response, and extracellular structure were enriched due to the antibiotic application. The observed effects were visible during the complete application phase and disappeared at the post-exposure phase.

CONCLUSIONS:
Our findings suggest that the oral administration of antibiotics increases the potential for MGE-mediated exchange of ARGs in the gut of fish and could contribute to the enrichment and dispersion of ARGs in aquaculture systems. Importantly, this increase in the potential for ARGs exchange could be an effect of changes in community structure and/or ARG mobilization.
https://www.ncbi.nlm.nih.gov/pubmed/30773139