摘要

在动物生产中使用抗菌药物已被证明可增加微生物中抗生素抗性基因（ARGs）的丰度，国际卫生组织建议限制使用抗菌生长促进剂。因此，生长促进剂替代品的使用越来越多，然而，它们对动物微生物群中ARGs（抵抗性）富集的影响尚不清楚。本文研究了不同生长促进剂对猪粪抗药性和微生物的影响。生长促进剂为卡巴多（抗生素）、硫酸铜和氧化锌（金属）或蘑菇粉（天然产物）。每次生长实验中，6栏断奶猪仔每栏7头用作一次处理，33天后，每栏取样一头中等体重母猪和公猪的粪便样本。从同一支栏采集的样本合并，分离DNA。用16s rRNA基因测序法研究了该群落的组成，并用382对引物测定了ARG和可移动基因元件（MGE）的相对丰度。生长促进剂组的群落结构和抗性变化不大，但与MGEs同时发生的ARGs比对照组多。在生长促进剂组中，分类学结构与抗性结构不相关。ARG-MGE共现模式表明，用替代性生长促进剂代替抗生素的使用可能是一种不充分的抗生素耐药性缓解策略，主动选择应对ARGs将需要更全面的方法。

The use of antimicrobials in animal production has been shown to increase the abundance of antibiotic resistance genes (ARGs) in microbiomes and it is recommended by international health organizations that the use of antimicrobial growth promoters would be restricted. Consequently, the use alternative growth promoters is increasing, however, their influence on the collection of ARGs (the resistome) in the animal microbiome is understudied. We investigated the impact of different growth promoters on the pig fecal resistome and microbiome. The growth promoters were carbadox (antibiotic), copper sulfate and zinc oxide (metal) or mushroom powder (natural product). Six pens of seven weanling piglets per treatment were used in a growth trial and after 33 days, fecal samples were taken from one median weight female and male pig per pen. Samples from the same pen were pooled, and DNA was isolated. The community composition was investigated by 16S rRNA gene sequencing and relative ARG and mobile genetic element (MGE) abundances were measured using qPCR array with 382 primers. Only modest shifts were observed in community structure and resistome in response to growth promoters, but more ARGs were co-occurring with MGEs in growth promoter group samples than in the control group samples. The taxonomic structure could not be linked to resistome structure in the growth promoter groups. The ARG–MGE co-occurrence patterns suggest that replacing the use of antibiotics with alternative growth promoters might be an insufficient antibiotic resistance mitigation strategy and active selection against ARGs will require a more comprehensive approach.

https://www.biorxiv.org/content/10.1101/2020.02.19.957100v1.abstract