BACKGROUND The majority of antimicrobials given during the production of pigs are given to nursery pigs. The influence of antimicrobial use on the levels of antimicrobial resistant (AMR) genes is important to quantify to be able to assess the impact of resistance on the food chain and risk to human and animal health. RESULTS This study investigated the response on the levels of nine AMR genes to five different treatment strategies with oxytetracycline, and the dynamics of gene abundance over time by following 1167 pigs from five different farms in Denmark. The results showed no significant difference between treatments and an increase in abundance for the efflux pump encoding tet(A) gene and the genes encoding the ribosomal protection proteins tet(O) and tet(W) tetracycline resistant genes following treatment, while tet(M) showed no response to treatment. However, it was also observed that the levels of tet(O), tet(W), and ermB in some farms would drift more over time compared to a single treatment-course with antibiotic. CONCLUSION This study underlines the large variation in AMR levels under natural conditions and the need for increased investigation of the complex interactions of antimicrobial treatment and other environmental and managerial practices in swine production on AMR gene abundance.

中文翻译：

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四环素治疗方案对保育猪随着时间推移抗生素抗性基因选择的影响。

背景技术在猪的生产过程中给予的大多数抗菌剂被给予种猪。抗菌药物使用对抗菌药物抗药性（AMR）基因水平的影响对于量化评估抗药性对食物链的影响以及对人类和动物健康的风险至关重要。结果本研究调查了五个土霉素对五种不同治疗策略的9种AMR基因水平的反应以及随时间推移的基因丰度动态，方法是跟踪丹麦5个不同农场的1167头猪。结果显示治疗之间无显着差异，处理后编码tet（A）基因和编码核糖体保护蛋白tet（O）和tet（W）四环素抗性基因的外排泵丰度增加，而tet（M）对治疗无反应。但是，还观察到，与单一抗生素疗程相比，某些农场中的tet（O），tet（W）和ermB的水平随着时间的推移会更多地漂移。结论这项研究强调了自然条件下AMR水平的巨大差异，并且有必要对AMR基因丰度方面在猪生产中抗菌治疗与其他环境和管理实践之间复杂的相互作用进行更多的研究。