Wastewater treatment plants are important reservoirs and sources for the dissemination of antibiotic resistance into the environment. Here, two different groups of carbapenem resistant bacteria—the potentially environmental and the potentially pathogenic—were isolated from both the wastewater influent and discharged effluent of a full-scale wastewater treatment plant and characterized by whole genome sequencing and antibiotic susceptibility testing. Among the potentially environmental isolates, there was no detection of any acquired antibiotic resistance genes, which supports the idea that their resistance mechanisms are mainly intrinsic. On the contrary, the potentially pathogenic isolates presented a broad diversity of acquired antibiotic resistance genes towards different antibiotic classes, especially β-lactams, aminoglycosides, and fluoroquinolones. All these bacteria showed multiple β-lactamase-encoding genes, some with carbapenemase activity, such as the bla_KPC-type genes found in the Enterobacteriaceae isolates. The antibiotic susceptibility testing assays performed on these isolates also revealed that all had a multi-resistance phenotype, which indicates that the acquired resistance is their major antibiotic resistance mechanism. In conclusion, the two bacterial groups have distinct resistance mechanisms, which suggest that the antibiotic resistance in the environment can be a more complex problematic than that generally assumed.

中文翻译：

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从污水处理厂分离出的耐环境和致病性碳青霉烯类细菌具有不同的抗生素抗性机制

污水处理厂是抗生素耐药性传播到环境中的重要蓄水池和来源。在这里，从大型污水处理厂的污水进水和出水中分离出两组不同的碳青霉烯类抗性细菌——潜在的环境细菌和潜在的致病细菌，并通过全基因组测序和抗生素敏感性测试进行表征。在潜在的环境分离株中，没有检测到任何获得性的抗生素抗性基因，这支持了它们的抗性机制主要是内在的这一观点。相反，潜在致病性分离株对不同抗生素类别表现出广泛多样的获得性抗生素抗性基因，尤其是 β-内酰胺类、氨基糖苷类、和氟喹诺酮类药物。所有这些细菌都显示出多个 β-内酰胺酶编码基因，其中一些具有碳青霉烯酶活性，例如在肠杆菌科分离物中发现的bla _KPC型基因。对这些分离株进行的抗生素药敏试验也表明，它们都具有多重耐药表型，这表明获得性耐药是其主要的抗生素耐药机制。总之，这两个细菌群具有不同的耐药机制，这表明环境中的抗生素耐药性可能比通常假设的更复杂。