摘要

       水平基因转移（HGT）在抗生素抗性基因的传播中起着重要作用。在下水道系统中，人类相关细菌和环境细菌混合在一起并暴露于许多已知会增加 HGT 的物质，包括各种抗菌化合物。在废水中，这些物质最常在低于已知单独诱导 HGT 的浓度下检测到。尽管如此，此类废水仍有可能引发 HGT，例如通过混合效应。在这里，一组抗生素、杀菌剂和其他药物在来自瑞典哥德堡的过滤消毒的市政和医院废水样本中进行了测量。通过将复杂的细菌供体群落与带有 GFP 标记的大肠杆菌受体菌株一起暴露来研究这些样品中化学混合物对 HGT 的影响。从细菌群落中捕获了赋予磺胺耐药性的移动遗传元件 (MGE) 的受体被列举出来，并通过复制子分型、抗生素敏感性测试和长读长测序进行表征。虽然暴露于城市废水不会导致 HGT 率发生任何可检测的变化，但暴露于医院废水与获得磺胺耐药性的接受者比例增加有关，但也与接受者总数急剧减少有关。尽管医院中的浓度通常高于城市废水，但没有一种测量物质可以单独解释所观察到的医院废水的影响。捕获的大多数 MGE 是 IncN 质粒，并且在大多数情况下共同转移了对几种抗生素的抗性。总之，数据显示没有证据表明所研究的城市废水中存在的化学物质会导致 HGT。尽管如此，接触医院废水后转接合子的相对丰度增加可能会对耐药细菌的出现和传播风险产生影响。

       Horizontal gene transfer (HGT) plays an important role in the dissemination of antibiotic resistance genes. In sewer systems, human-associated and environmental bacteria are mixed together and exposed to many substances known to increase HGT, including various antibacterial compounds. In wastewaters, those substances are most often detected below concentrations known to induce HGT individually. Still, it is possible that such wastewaters induce HGT, for example via mixture effects. Here, a panel of antibiotics, biocides and other pharmaceuticals was measured in filter-sterilized municipal and hospital wastewater samples from Gothenburg, Sweden. The effects on HGT of the chemical mixtures in these samples were investigated by exposing a complex bacterial donor community together with a GFP-tagged E. coli recipient strain. Recipients that captured sulfonamide resistance-conferring mobile genetic elements (MGEs) from the bacterial community were enumerated and characterized by replicon typing, antibiotic susceptibility testing and long read sequencing. While exposure to municipal wastewater did not result in any detectable change in HGT rates, exposure to hospital wastewater was associated with an increase in the proportion of recipients that acquired sulfonamide resistance but also a drastic decrease in the total number of recipients. Although, concentrations were generally higher in hospital than municipal wastewater, none of the measured substances could individually explain the observed effects of hospital wastewater. The great majority of the MGEs captured were IncN plasmids, and resistance to several antibiotics was co-transferred in most cases. Taken together, the data show no evidence that chemicals present in the studied municipal wastewater induce HGT. Still, the increased relative abundance of transconjugants after exposure to hospital wastewater could have implications for the risks of both emergence and transmission of resistant bacteria.

https://www.sciencedirect.com/science/article/pii/S0269749121003134