Using molecular and whole-genome sequencing tools, we investigated colistin-resistant Escherichia coli isolates from wild sea lions. Two unrelated E. coli colistin-resistant isolates, ST8259 and ST4218, were identified, both belonging to the B2 phylogroup and different serotypes. Polymorphisms in PmrA, PmrB, and PhoQ proteins were identified, and the role of PmrB and PhoQ in contributing to colistin resistance was determined by complementation assays. However, the mutations characterized in the present study are not involved in colistin resistance, which have been described in E. coli isolates from clinical settings. Therefore, the acquired mutations in pmrB and phoQ genes in resistance to colistin in bacteria related to marine environment animals are different. This work contributes to the surveillance and characterization of colistin resistance in Escherichia coli obtained from animals from aquatic environments.

中文翻译：

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来自野生海狮（Zalophus californianus）的耐粘菌素大肠杆菌分离株的分子和基因组特征

使用分子和全基因组测序工具，我们研究了从野生海狮中分离出的耐粘菌素的大肠杆菌。鉴定出两种不相关的大肠杆菌耐药菌株 ST8259 和 ST4218，均属于 B2 系统群和不同的血清型。鉴定了 PmrA、PmrB 和 PhoQ 蛋白的多态性，并通过互补测定确定了 PmrB 和 PhoQ 在促进粘菌素抗性中的作用。然而，本研究中表征的突变不涉及粘菌素耐药性，这已在临床环境中的大肠杆菌分离株中进行了描述。因此，与海洋环境动物相关的细菌对粘菌素耐药的pmrB和phoQ基因的获得性突变是不同的。