College of Veterinary Medicine, Henan Agricultural University, Zhengzhou 450046, PR China.
College of Veterinary Medicine, Henan Agricultural University, Zhengzhou 450046, PR China.
Int J Food Microbiol. 2022 Dec 2;382:109914. doi: 10.1016/j.ijfoodmicro.2022.109914. Epub 2022 Sep 6.
Carbapenems and fosfomycin are important antibiotics used to treat Enterobacteriaceae-associated infections. This study aimed to characterize the co-resistance and co-dissemination mechanism of carbapenem and fosfomycin resistance in an Escherichia coli ST117 strain isolated from retail chicken meat. Antimicrobial susceptibility testing showed that an E. coli CS18F strain had a multidrug resistance profile, including carbapenem and fosfomycin resistance. The presence of bla and fosA3 genes was confirmed by PCR and Sanger sequencing. The bla and fosA3 genes were successfully transferred to the recipient strain E. coli J53 via conjugation, and the transconjugants had elevated minimum inhibitory concentrations (MICs) for meropenem and fosfomycin. Whole genome sequencing (WGS) of E. coli CS18F revealed that bla and fosA3 were colocalized on an IncFIA/FIB/FIC(FII) type plasmid of 189,141 bp, which was designated as pCS18F-NDM-Fos. A novel structure with five IS26 sequences flanking the multiple drug resistance region (MDRR) was identified, and three copies of IS26 were found to be flanked bla, fosA3, dfrA12, aadA2, and sul1. Three types of translocation units (TUs) were identified by PCR, containing either the resistance gene bla and an IS26 sequence, fosA3, and an IS26 sequence, or both, indicating their potential co-transfer via TUs. Thus, this is an unprecedented report of the presence of a plasmid co-carrying bla and fosA3 and TUs potentially mediating their simultaneous transfer.
碳青霉烯类和磷霉素是用于治疗肠杆菌科相关感染的重要抗生素。本研究旨在表征从零售鸡肉中分离出的一株大肠杆菌 ST117 中碳青霉烯和磷霉素耐药的共同耐药和共同传播机制。药敏试验表明，一株大肠杆菌 CS18F 菌株具有多药耐药表型，包括碳青霉烯类和磷霉素耐药。PCR 和 Sanger 测序证实了 bla 和 fosA3 基因的存在。bla 和 fosA3 基因通过接合成功转移到受体菌株大肠杆菌 J53 中，转导子对美罗培南和磷霉素的最小抑菌浓度（MIC）升高。大肠杆菌 CS18F 的全基因组测序（WGS）显示，bla 和 fosA3 位于一个 189,141 bp 的 IncFIA/FIB/FIC(FII) 型质粒上，该质粒被命名为 pCS18F-NDM-Fos。鉴定出一种新型结构，其多药耐药区（MDRR）周围有五个 IS26 序列，发现三个 IS26 拷贝位于 bla、fosA3、dfrA12、aadA2 和 sul1 侧翼。通过 PCR 鉴定出三种类型的转位单元（TU），包含 bla 和 IS26 序列、fosA3 和 IS26 序列或两者都有，表明它们可能通过 TU 同时转移。因此，这是首次报道存在同时携带 bla 和 fosA3 的质粒和可能介导其同时转移的 TU。
