Resistance to the "last resort" antibiotics, such as carbapenems, has led to very few antibiotics being left to treat infections by multi-drug resistant bacteria. Spread of carbapenem resistance (CR) has been well characterised for the clinical environment. However, there is lack of information about its environmental distribution. Our study first reveals that CR is present in a wide range of Gram-negative bacteria in the coastal seawater environment, including four phyla, eight classes, and 30 genera. These bacteria were likely introduced into seawater via stormwater flows. Some CR isolates found, such as Acinetobacter junii, A. johnsonii, Brevundimonas vesicularis, Enterococcus durans, Pseudomonas monteilii, P. fulva, and Stenotrophomonas maltophilia, are relevant to human health. We also describe a novel Metallo-β-lactamase (MBL) for marine Rheinheimera isolates with CR, which has likely been horizontally transferred to Citrobacter freundii or Enterobacter cloacae. In contrast, another MBL of the New Delhi Metallo ß-lactamase (NDM)-type was likely acquired by environmental Variovorax isolates with CR from Escherichia coli, Klebsiella pneumoniae, or Acinetobacter baumannii utilizing a plasmid. Our findings add to the growing body of evidence that the aquatic environment is both a reservoir and a vector for novel CR genes.

Importance

Antibiotic resistance against the "last resort" antibiotics of the carbapenem family is often based on the production of carbapenemases and this has been frequently observed in clinical samples. However, the dissemination of carbapenem resistance (CR) in the environment has been less well explored. Our study shows that CR is commonly found in a range of bacterial taxa in the coastal aquatic environment and can involve the exchange of novel Metallo-β-lactamase from typical environmental bacteria to potential human pathogens or vice versa. The outcomes of this study contribute to a better understanding of how aquatic and marine bacteria can act as reservoirs and vectors for CR outside the clinical setting.

对诸如碳青霉烯等“最后手段”的抗生素的耐药性导致几乎没有抗生素可用于治疗多药耐药细菌的感染。碳青霉烯耐药性（CR）的传播已针对临床环境进行了很好的表征。但是，缺乏有关其环境分布的信息。我们的研究首先揭示了CR在沿海海水环境中存在于多种革兰氏阴性细菌中，包括四个门，八个类别和30个属。这些细菌很可能是通过雨水流引入海水的。发现了一些CR分离株，如不动杆菌，约翰逊曲霉，水疱短杆菌，杜伦肠球菌，蒙特雷假单胞菌，富叶疟原虫和嗜麦芽窄食单胞菌。与人类健康有关。我们还描述了一种新型的Metallo-β-内酰胺酶（MBL），用于带有RCR的海生莱茵大肠埃希菌分离株，它可能已水平转移至弗氏柠檬酸杆菌或阴沟肠杆菌。相反，另一种新德里金属β-内酰胺酶（NDM）型MBL可能是通过带有质粒的环境Variovorax带CR的分离株从大肠杆菌，肺炎克雷伯菌或鲍曼不动杆菌中获得的。我们的发现增加了越来越多的证据，表明水生环境既是新型CR基因的储存库又是载体。

重要性

对碳青霉烯家族的“最后手段”抗生素的抗生素抗性通常基于碳青霉烯酶的产生，并且在临床样品中经常观察到这种情况。然而，对碳青霉烯抗性（CR）在环境中的传播尚未得到很好的研究。我们的研究表明，CR通常在沿海水生环境中的一系列细菌类群中发现，并且可能涉及将新型Metallo-β-内酰胺酶从典型的环境细菌交换为潜在的人类病原体，反之亦然。这项研究的结果有助于更好地了解水生和海洋细菌如何在临床环境之外充当CR的储存库和载体。