据一项新的研究报告称，土壤细菌和人类病原体会快速地交换药耐药性基因，提示环境中的细菌可促进抗生素耐药性危机。这些发现可改变目前的有关抗生素耐药性及对付它的方法的想法。土壤是地球上最大、最多元的微生物生境之一；它被人们越来越多地认识到是抗生素耐药基因的一个巨大的来源。土壤不但会直接与广泛用于牲畜饲养和种植农业的抗生素接触，它也是链霉菌的一个天然栖息地；链霉菌中的各种类型占了所有自然产生的抗生素中的主体。Kevin Forsberg及其同事用元基因组测序来寻找与在沙门氏菌、肺炎克雷伯菌及其它致病病原体等不同菌株中有着完全同一性的农田土壤细菌中的7种抗药基因。 他们还发现，多种抗药基因簇集在一起并在其两侧有已知能够使细菌之间发生基因转移的移动DNA元件。 尽管这一研究的设立并非是为了确定土栖生物体与人类病原体之间是如何交换基因的，但这些结果提示，含有高浓度抗生素的排泄物对土壤和水的污染，以及在牲畜饲养中过度使用抗生素可能是在环境细菌中出现抗生素耐药基因选择的促成因素。（生物谷Bioon.com）
doi: 10.1126/science.1220761
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The Shared Antibiotic Resistome of Soil Bacteria and Human Pathogens
Kevin J. Forsberg, Alejandro Reyes, Bin Wang, Elizabeth M. Selleck, Morten O. A. Sommer, Gautam Dantas
Soil microbiota represent one of the ancient evolutionary origins of antibiotic resistance and have been proposed as a reservoir of resistance genes available for exchange with clinical pathogens. Using a high-throughput functional metagenomic approach in conjunction with a pipeline for the de novo assembly of short-read sequence data from functional selections (termed PARFuMS), we provide evidence for recent exchange of antibiotic resistance genes between environmental bacteria and clinical pathogens. We describe multidrug-resistant soil bacteria containing resistance cassettes against five classes of antibiotics (β-lactams, aminoglycosides, amphenicols, sulfonamides, and tetracyclines) that have perfect nucleotide identity to genes from diverse human pathogens. This identity encompasses noncoding regions as well as multiple mobilization sequences, offering not only evidence of lateral exchange but also a mechanism by which antibiotic resistance disseminates.
