目标
评估饲料中施用的抗生素对鸡肠中大肠杆菌的抗性表型和基因型的影响。

方法和结果
在饲料中给予鸡阿莫西林，金霉素和氟苯尼考，并检查203肠道大肠杆菌对11种抗微生物剂的敏感性以及使用PCR存在抗生素抗性基因。在15,20,30和40日龄鸡中从鸡粪样品中提取DNA。我们发现虽然抗生素耐药率随时间增加，但tet（W），tet（A），cmlA，cfr和sul1的相对基因丰度下降。相反，基因blaTEM和mcr-1的相对丰度在实验期间增加。 Pearson相关分析表明，sul1与tet（W）相关（R = 0.630，p <0.01），cmlA与cfr相关（R = 0.587，p <0.01）。有趣的是，mcr-1与tet（W）相关（R = -0.546，p <0.05）。

结论
施用不同的抗生素降低了鸡中抗生素抗性基因的相对丰度，但没有阻止抗生素抗性的扩大。

研究的意义和影响
改变用于预防鸡的抗生素抗性的抗生素类型的模式不是防止抗生素抗性基因扩散的可行方法。

Aim

To assess the effect of antibiotics administered in feed on the resistance phenotypes and genotypes of Escherichia coli in the chicken intestine.

Method and Results
Chickens were administered amoxicillin, chlortetracycline and florfenicol in feed and 203 intestinal E. coli were examined for their susceptibility to 11 antimicrobial agents and for the presence of antibiotic resistance genes using PCR. DNA was extracted from chicken stool samples in 15, 20, 30 and 40 day old chickens. We found that while antibiotic resistance rates increased with time, the relative gene abundance of tet(W), tet(A), cmlA, cfr and sul1 decreased. In contrast, the relative abundance of gene blaTEM and mcr‐1 increased over the experimental period. Pearson correlation analysis indicated that sul1 was correlated with tet(W) (R=0.630, p < 0.01) and cmlA correlated with cfr (R=0.587, p < 0.01). Interestingly, mcr‐1 correlated with tet(W) (R=‐0.546, p < 0.05).

Conclusions
Administration of different antibiotic reduced the relative abundance of antibiotic resistance genes in chickens but did not halt the expansion of antibiotic resistance.

Significance and Impact of the Study

Changing the pattern of antibiotic types used to prevent antibiotic resistance in chickens is not a viable method to prevent the spread of antibiotic resistance genes.

https://onlinelibrary.wiley.com/doi/abs/10.1111/jam.14065