摘要

      环境抵抗素已被公认为抗生素抗性基因的起源和储库，并被认为是活跃的和不断扩大的。在这项研究中，目的基因测序表明，氨基糖苷类失活酶AAC（6'） - Ib的多态性多样性具有生态位特异性。 AAC（6'） - Ib-cr，以前被称为临床变异体，在各种土壤、鸡和人的肠道中普遍存在，表明这种变异体可能不是由临床上的适应性突变引起的，而是来源于环境。此外，AAC（6'） - Ib的生态显性多态性变体进行表征，发现其对喹诺酮类和氨基糖苷类具有不同的底物特异性，从而赋予其改变的耐药谱。有趣的是，D179Y取代的新型变体显示出对新开发的氟喹诺酮吉氟沙星显示出扩展的抗性谱。我们的结果表明，土壤微生物群和动物微生物群可能是抗生素抗性的主要宿主;多态多样性扩大了环境中的抗生素抗性基因，导致新的潜在抗性出现。

     The environmental resistome has been recognized as the origin and reservoir of antibiotic resistance genes and considered to be dynamic and ever expanding. In this study, a targeted gene sequencing approach revealed that the polymorphic diversity of the aminoglycoside-inactivating enzyme AAC(6′)-Ib was ecological niche-specific. AAC(6′)-Ib-cr, previously known as a clinical variant, was prevalent in various soils and the intestines of chickens and humans, suggesting that this variant might not have arisen from adaptive mutations in the clinic but instead originated from the environment. Furthermore, ecologically dominant polymorphic variants of AAC(6′)-Ib were characterized and found to display different substrate specificities for quinolones and aminoglycosides, conferring the altered resistance spectra. Interestingly, a novel variant with the D179Y substitution showed an extended resistance spectrum to the recently developed fluoroquinolone gemifloxacin. Our results suggest that soil and animal microbiomes could be major reservoirs of antibiotic resistance; polymorphic diversity expands the antibiotic resistome in the environment, resulting in the potential emergence of novel resistance.

https://www.nature.com/articles/ismej2017168