1月19日,，根據(jù)美國密歇根州立大學和美國農(nóng)業(yè)部農(nóng)業(yè)研究中心的共同研究結果，在豬食中添加抗生素成分將增強生豬體內(nèi)腸道微生物對抗生素藥物的抗藥性,。
有關這一研究的相關論文已經(jīng)發(fā)表在了最新一期的美國《國家科學院學報》，該項研究的目的旨在幫助科學家們理解在美國農(nóng)場中備受爭議的在豬食中添加抗生素的做法將可能產(chǎn)生的影響,。數(shù)十年來,，美國境內(nèi)的很多農(nóng)場都會在他們飼養(yǎng)的牲畜飼料中添加抗生素，不管是豬,，家禽還是其它農(nóng)場動物,，情況都是如此。農(nóng)場主們這樣做的目的首先是防止動物們患病,，其次還可以加速牲畜的生長速率并提高飼料產(chǎn)出效率,。
密歇根州立大學微生物學和分子遺傳學教授詹姆斯·提亞杰(James Tiedje)表示，科學家們目前尚無法解釋為何抗生素的攝入會加速動物身體的成長并由此提升飼料產(chǎn)出效率,，但是他們擔心這種抗生素的添加將增強牲畜體內(nèi)微生物對多種存在爭議的抗生素藥物的抗藥性,，這些抗生素藥物對于人體和動物本身的健康存在潛在的風險。他說：“病原體的抗生素藥物抗藥性變強對于全世界來說都將是一個巨大的挑戰(zhàn),。因此了解究竟是何種機制導致這種增強效應,，以及如何去控制它是至關重要的。”
其它研究進展還包括：
1,、在飼料添加抗生素的豬腸道內(nèi)的微生物群落中細菌的抗藥性基因種類和數(shù)量均出現(xiàn)了增加,，但仍需進一步的長期研究；
2,、在這些生豬體內(nèi)發(fā)現(xiàn)的一些基因是出乎意料的,，通常它們和一些并未在研究中使用過的抗生素有關；
3,、在食用抗生素添加物飼料的生豬體內(nèi),，與生長有關的微生物基因和微生物消耗的能量大量增加，這可能暗示了抗生素藥物與動物生長加速以及飼料產(chǎn)出率之間存在的某種聯(lián)系,；
4,、在食用抗生素添加物飼料的生豬體內(nèi),，大腸桿菌菌群數(shù)量出現(xiàn)上升。但仍需進一步觀察以驗證這一結論,；
美國農(nóng)業(yè)部研究人員托里·羅夫特(Torey Looft)說：“據(jù)我們所知,，這是首次針對農(nóng)場飼料中抗生素的添加產(chǎn)生何種影響進行的專門研究。借助綜合手段觀察牲畜腸道菌群的功能及組成方面發(fā)生的變化,。”(生物谷 Bioon.com)
doi:10.1073/pnas.1120238109
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PMID:
In-feed antibiotic effects on the swine intestinal microbiome
Torey Looft, Timothy A. Johnson, Heather K. Allen, Darrell O. Bayles, David P. Alt, Robert D. Stedtfeld, Woo Jun Sul, Tiffany M. Stedtfeld, Benli Chai, James R. Cole, Syed A. Hashsham, James M. Tiedje, and Thad B. Stanton
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.
