The aim of this work was to detect Escherichia coli isolates displaying resistance to oxyimino-cephalosporins, quinolones, and colistin in feces from livestock in Uruguay. During 2016–2019, fecal samples from 132 broiler and layer chicken flocks, 100 calves, and 50 pigs, were studied in Uruguay. Samples were cultured on MacConkey Agar plates supplemented with ciprofloxacin, ceftriaxone, or colistin. E. coli isolates were identified by mass spectrometry and antibiotic susceptibility testing was performed by disk diffusion agar method and colistin agar test. Antibiotic resistance genes were detected by polymerase chain reaction and sequencing. The most frequently detected resistance gene was qnrB19, recovered from 87 animals. Regarding plasmid-mediated quinolone resistance genes, qnrS1 was the second in prevalence (23 animals) followed by qnrE1, found in 6 chickens and two calves. Regarding resistance to oxyimino-cephalosporins, 8 different β-lactamase genes were detected: bla_CTX−M−8 and bla_CMY−2 were found in 23 and 19 animals, respectively; next, bla_CTX−M−2 and bla_SHV−12 in 7 animals each, followed by bla_CTX−M−14 in 5, bla_CTX−M−15 and bla_SHV2a in 2, and bla_CTX−M−55 in a single animal. Finally, the mcr-1 gene was detected only in 8 pigs from a single farm, and in a chicken. Isolates carrying bla_CMY−2 and bla_SHV−12 were also found in these animals, including two isolates featuring the bla_CMY−2/mcr-1 genotype. To the best of our knowledge, this is the first work in which the search for transferable resistance to highest priority critically important antibiotics for human health is carried out in chickens and pigs chains of production animals in Uruguay.

这项工作的目的是检测乌拉圭牲畜粪便中对氧亚氨基头孢菌素、喹诺酮类药物和粘菌素具有抗性的大肠杆菌分离株。 2016 年至 2019 年期间，对乌拉圭 132 只肉鸡和蛋鸡群、100 头牛犊和 50 头猪的粪便样本进行了研究。样品在补充有环丙沙星、头孢曲松或粘菌素的麦康凯琼脂平板上培养。通过质谱法鉴定大肠杆菌分离株，并通过纸片扩散琼脂法和粘菌素琼脂试验进行抗生素敏感性测试。通过聚合酶链反应和测序检测抗生素抗性基因。最常检测到的抗性基因是 qnrB19，从 87 只动物中回收。关于质粒介导的喹诺酮抗性基因，qnrS1 的患病率位居第二（23 只动物），其次是 qnrE1，在 6 只鸡和 2 只小牛中发现。关于氧亚氨基头孢菌素耐药性，检测到 8 种不同的 β-内酰胺酶基因：分别在 23 只和 19 只动物中发现了 bla _CTX−M−8和 bla _CMY−2 ；接下来，各 7 只动物中的 bla _CTX−M−2和 bla _SHV−12 ，随后是 5 只动物中的 bla _{CTX−M−14，2}只动物中的 bla _CTX−M−15和 bla _SHV2a ，以及 1 只动物中的 bla _CTX−M−55 。单一动物。最后，仅在同一农场的 8 头猪和一只鸡中检测到 mcr-1 基因。在这些动物中还发现了携带 bla _CMY−2和 bla _SHV−12的分离株，其中包括两个具有 bla _CMY−2 /mcr-1 基因型的分离株。 据我们所知，这是首次在乌拉圭的鸡和猪生产动物链中寻找对人类健康至关重要的抗生素的可转移耐药性。