人们已经对农业动物使用了50多年的抗生素从而改善生产，近日发表在PNAS杂志上的一项研究"In-feed antibiotic effects on the swine intestinal microbiome"证实：这可能增强耐抗生素基因并增加埃希氏大肠杆菌在猪粪中的散发。
Looft及其同事评估了资料中的抗生素对猪的肠道微生物群的作用。这组作者让一组小猪食用没有药的饲料，而让另一组食用添加了氯四环素、磺胺甲嘧啶以及青霉素的性能增强混合物的饲料。
对粪样本的遗传分析显示，食用了抗生素的小猪体内的变形菌门微生物的成员是没有食用抗生素的小猪的10倍以上，这特别是由于埃希氏大肠杆菌中群的增加。
另外的定量与统计分析表明，与能量生产和转化有关的微生物功能基因的表达在食用抗生素的猪的体内增加。这些食用了药物的猪的耐抗生素基因的丰富程度和多样性增加。这组作者说，这些发现提示应该谨慎地让动物和人类使用抗生素，而进一步的研究应该把重点放在抗生素替代品的开发上。（生物谷Bioon.com）
doi:10.1073/pnas.1120238109
PMC:
PMID:
In-feed antibiotic effects on the swine intestinal microbiome
Torey Loofta,1, Timothy A. Johnsonb,c,1, Heather K. Allena,1, Darrell O. Baylesa, David P. Alta, Robert D. Stedtfeldb,d, Woo Jun Sulb,c, Tiffany M. Stedtfeldb, Benli Chaib, James R. Coleb, Syed A. Hashshamb,d, James M. Tiedjeb,c,2, and Thad B. Stantona,2
Antibiotics have been administered to agricultural animals for disease treatment, disease prevention, and growth promotion for over 50 y. The impact of such antibiotic use on the treatment of human diseases is hotly debated. We raised pigs in a highly controlled environment, with one portion of the littermates receiving a diet containing performance-enhancing antibiotics [chlortetracycline, sulfamethazine, and penicillin (known as ASP250)] and the other portion receiving the same diet but without the antibiotics. We used phylogenetic, metagenomic, and quantitative PCR-based approaches to address the impact of antibiotics on the swine gut microbiota. Bacterial phylotypes shifted after 14 d of antibiotic treatment, with the medicated pigs showing an increase in Proteobacteria (1–11%) compared with nonmedicated pigs at the same time point. This shift was driven by an increase in Escherichia coli populations. Analysis of the metagenomes showed that microbial functional genes relating to energy production and conversion were increased in the antibiotic-fed pigs. The results also indicate that antibiotic resistance genes increased in abundance and diversity in the medicated swine microbiome despite a high background of resistance genes in nonmedicated swine. Some enriched genes, such as aminoglycoside O-phosphotransferases, confer resistance to antibiotics that were not administered in this study, demonstrating the potential for indirect selection of resistance to classes of antibiotics not fed. The collateral effects of feeding subtherapeutic doses of antibiotics to agricultural animals are apparent and must be considered in cost-benefit analyses.
