The environment is considered a major reservoir of antimicrobial resistant microorganisms (AMR) and antimicrobial resistance genes (ARG). Colistin, a “last resort” antibiotic, is used for the treatment of severe infections caused by multidrug-resistant Gram-negative bacteria. The global dissemination of mobile colistin resistance genes (mcr) in natural and non-natural environments is a major setback in the fight against antimicrobial resistance. Hitherto, there is a limited number of studies screening this resistance determinant in bacteria from wildlife. In this study, we describe for the first time the detection of plasmid-mediated colistin resistance in Escherichia coli from wild ungulates in Portugal, which are also widely distributed across Europe. This information is critical to identify the importance of ungulates in the dissemination of resistant bacteria, and their corresponding genes, across the environment. Here, 151 resistant-Enterobacteriaceae isolated from 181 samples collected from different wild ungulate species throughout Portugal were screened for mcr genes. Four mcr-1-positive Escherichia coli were detected from four fallow deer individuals that were sampled in the same hunting ground. These four isolates harboured mcr-1-related IncP plasmids belonging to sequencing types ST155, ST533 and ST345 (n = 2), suggesting bacterial and/or plasmid circulation. All mcr-1-positive E. coli also showed other resistance phenotypes, including MDR, including the B1 commensal phylogenetic profile. All mcr-1-positive E. coli show additional resistance phenotypes, including MDR, including the B1 commensal phylogenetic profile. Our findings are upsetting, highlighting the global dissemination of colistin resistance genes in the whole ecosystem, which, under the One Health framework, emphasizes the urgent need for effective implementation of AMR surveillance and control in the human-animal-environment interfaces.

环境被认为是抗菌素耐药微生物 (AMR) 和抗菌素耐药基因 (ARG) 的主要储存库。粘菌素是一种“最后的手段”抗生素，用于治疗由多重耐药革兰氏阴性菌引起的严重感染。移动粘菌素耐药基因 ( mcr ) 在自然和非自然环境中的全球传播是抗击抗菌素耐药性的重大挫折。迄今为止，在野生动物细菌中筛选这种耐药性决定因素的研究数量有限。在这项研究中，我们首次描述了在大肠杆菌中检测质粒介导的粘菌素耐药性来自葡萄牙的野生有蹄类动物，它们在欧洲也广泛分布。这些信息对于确定有蹄类动物在耐药细菌及其相应基因在环境中传播的重要性至关重要。在这里，从整个葡萄牙不同野生有蹄类动物物种收集的 181 个样本中分离出的 151 种抗性肠杆菌科进行了mcr基因的筛选。从在同一猎场取样的四只小鹿个体中检测到四只mcr-1阳性大肠杆菌。这四个分离株含有mcr - 1相关的 IncP 质粒，属于测序类型 ST155、ST533 和 ST345（n = 2），表明存在细菌和/或质粒循环。全部mcr-1阳性大肠杆菌还显示出其他抗性表型，包括 MDR，包括 B1 共生系统发育谱。所有mcr-1阳性大肠杆菌都显示出额外的抗性表型，包括 MDR，包括 B1 共生系统发育谱。我们的发现令人不安，突出了整个生态系统中粘菌素抗性基因的全球传播，这在 One Health 框架下强调了在人-动物-环境界面中有效实施 AMR 监测和控制的迫切需要。