The expansion of mcr-carrying bacteria is a well-recognized public health problem. Measures to contain mcr spread have mainly been focused on the food–animal production sector. Nevertheless, the spread of MCR producers at the environmental interface particularly driven by the increasing population of gulls in coastal cities has been less explored. Occurrence of mcr-carrying Escherichia coli in gull's colonies faeces on a Portuguese beach was screened over 7 months. Cultural, molecular and genomic approaches were used to characterize their diversity, mcr plasmids and adaptive features. Multidrug-resistant mcr-1-carrying E. coli were detected for 3 consecutive months. Over time, multiple strains were recovered, including zoonotic-related pathogenic E. coli clones (e.g. B2-ST131-H22, A-ST10 and B1-ST162). Diverse mcr-1 genetic environments were mainly associated with ST2/ST4-HI2 (ST10, ST131, ST162, ST354 and ST4204) but also IncI2 (ST12990) plasmids or in the chromosome (ST656). Whole-genome sequencing revealed enrichment of these strains on antibiotic resistance, virulence and metal tolerance genes. Our results underscore gulls as important spreaders of high-priority bacteria and genes that may affect the environment, food–animals and/or humans, potentially undermining One-Health strategies to reduce colistin resistance.

中文翻译：

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海鸥中携带 mcr-1 的致病性大肠杆菌克隆的高度多样性强调了环境-牲畜-人界面策略的必要性

携带mcr的细菌的扩张是一个公认的公共卫生问题。遏制mcr传播的措施主要集中在食品-动物生产部门。然而，MCR 生产者在环境界面的传播，特别是在沿海城市海鸥数量增加的推动下，却很少被探索。对葡萄牙海滩上的海鸥群粪便中携带 mcr的大肠杆菌进行了 7 个月的筛查。文化、分子和基因组方法被用来表征它们的多样性、mcr质粒和适应性特征。携带多药耐药mcr -1 的大肠杆菌。大肠杆菌连续3个月被发现。随着时间的推移，恢复了多种菌株，包括人畜共患病相关的致病大肠杆菌。大肠杆菌克隆（例如 B2-ST131-H22、A-ST10 和 B1-ST162）。不同的mcr -1 遗传环境主要与 ST2/ST4-HI2 (ST10、ST131、ST162、ST354 和 ST4204) 以及 IncI2 (ST12990) 质粒或染色体 (ST656) 相关。全基因组测序揭示了这些菌株在抗生素抗性、毒力和金属耐受性基因上的富集。我们的研究结果强调，海鸥是可能影响环境、食物-动物和/或人类的高优先级细菌和基因的重要传播者，可能会破坏减少粘菌素耐药性的 One-Health 策略。