摘要

      牲畜中细菌的抗微生物耐药性（AMR）是一个日益严重的问题，部分原因是抗菌药物的不当使用。抗菌药物的使用（AMU）发生在瑞典奶牛场，但仅限于根据兽医的处方治疗生病的动物。尽管有这些严格的规定，奶牛场和屠宰场都有小牛脱落抗微生物肠杆菌的记录。然而，目前尚不清楚这些细菌是如何传播到奶牛场周围的当地环境中的。在这项研究中，我们从四个动物来源（小牛、鸟类和啮齿动物以及整只苍蝇的粪便样本）和两个环境来源（牛粪沟和粪坑）收集了样本。从样品中分离出大肠杆菌，并进行抗菌药物敏感性测试。对分离株的子集进行全基因组测序，以评估来源和基因组决定因素（如抗微生物耐药性基因（ARGs））之间的相关性，并评估质粒的存在。我们同时检测到ARGs、可移动遗传元件和低AMR发病率。特别是，我们在两种不同的动物来源中观察到了四种潜在的细菌克隆共享实例。这证明了耐大肠杆菌在奶牛场内、小牛和食腐动物（啮齿动物和苍蝇）之间传播的潜力。AMR传播和人畜共患AMR的风险在AMU低且受限制的国家通常较低。然而，我们表明，种间传播确实会发生，在几乎没有AMU限制的国家，这种风险可能被低估了。Antimicrobial resistance (AMR) in bacteria in the livestock is a growing problem, partly due to inappropriate use of antimicrobial drugs. Antimicrobial use (AMU) occurs in Swedish dairy farming but is restricted to the treatment of sick animals based on prescription by a veterinary practitioner. Despite these strict rules, calves shedding antimicrobial resistant Enterobacteriaceae have been recorded both in dairy farms and in slaughterhouses. Yet, not much is known how these bacteria disseminate into the local environment around dairy farms. In this study, we collected samples from four animal sources (fecal samples from calves, birds and rodents, and whole flies) and two environmental sources (cow manure drains and manure pits). From the samples, Escherichia coli was isolated and antimicrobial susceptibility testing performed. A subset of isolates was whole genome sequenced to evaluate relatedness between sources and genomic determinants such as antimicrobial resistance genes (ARGs) and the presence of plasmids were assessed. We detected both ARGs, mobile genetic elements and low rates of AMR. In particular, we observed four potential instances of bacterial clonal sharing in two different animal sources. This demonstrates resistant E. coli dissemination potential within the dairy farm, between calves and scavenger animals (rodents and flies). AMR dissemination and the zoonotic AMR risk is generally low in countries with low and restricted AMU. However, we show that interspecies dissemination does occur, and in countries that have little to no AMU restrictions this risk could be under-estimated.

https://www.frontiersin.org/articles/10.3389/fmicb.2022.838339/full