To clarify the persistence of extended‐spectrum β‐lactamase (ESBL) producers, 13 plasmids from two broiler farms were analyzed. On the farm not using antimicrobials, one plasmid from Klebsiella pneumoniae isolated from a day‐old chick was similar to that from Escherichia coli isolated a year later, with the deletion of two transposons. On the farm using antimicrobials, most circulating plasmids (eight out of nine) in a flock of 40‐days‐old chicks were identical, although one from K. pneumoniae had a deletion of a transposon carrying a class 1 integron containing aadA2 and dfrA12. Thus, ESBL plasmids persisted in the farms with or without antimicrobial agent use.

中文翻译：

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商业肉鸡场肠杆菌科细菌中广谱β-内酰胺酶质粒的持久性。

为了阐明超广谱β-内酰胺酶（ESBL）生产者的持久性，对来自两个肉鸡场的13个质粒进行了分析。在没有使用抗菌剂的农场中，从一天大的小鸡中分离出的肺炎克雷伯菌的一种质粒与一年后分离的大肠埃希菌的质粒相似，但缺失了两个转座子。在使用抗菌药物的农场中，一群40天大的雏鸡中的大多数循环质粒（九种中的八种）是相同的，尽管肺炎克雷伯菌中的一种具有含有aadA2和dfrA12的1类整合子的转座子缺失。因此，无论是否使用抗微生物剂，ESBL质粒都能在农场中持续存在。