Background

Nontyphoid Salmonella and Shigella can cause gastroenteritis in humans. Ceftriaxone (CRO) has been used to treat their infection, however, development of CRO resistance are often associated with plasmid-mediated bla_CMY. Here, we investigated the presence of plasmid-mediated ISEcp-1 tnpA-bla_CMY-2-blc-sugE and the role of these genes in regulation of CRO susceptibility in different hosts.

Methods

194 strains of Salmonella serovars and Shigella were tested for CRO susceptibility. Non-susceptibility strains were examined for plasmid-mediated ISEcp-1 tnpA-bla_CMY-2-blc-sugE by PCR amplification, Southern blot, and DNA sequencing. The plasmid profiles were determined by HindIII-digested restriction fragment length polymorphism (RFLP). Four recombinant plasmids with different genes from ISEcp-1 tnpA-bla_CMY-2-blc-sugE were constructed and then were transferred into Escherichia coli and different Salmonella serovars to evaluate the CRO susceptibility.

Results

Among 20 CRO-nonsusceptible isolates of Salmonella Choleraesuis (5), S. Typhimurium (4), S. Mons (1), S. Stanley (2) and Shigella sonnei (8) with plasmid-mediated bla_CMY-2, 19 isolates carried the ISEcp-1 tnpA-bla_CMY-2-blc-sugE and only one isolate with tnpA-bla_CMY-2. Transformation of these plasmids into E. coli pir116 produced multidrug resistance. Furthermore, PCR-RFLP analysis determined 5 different plasmid profiles and identical RFLP pattern between S. Typhimurium and S. sonnei. Transformation of the recombinant plasmids into E. coli and different Salmonella serovars resulted in phenotypes ranging from susceptible to resistant (especially inducible resistance) to CRO that were dependent on the genes, and host.

Conclusion

The CRO susceptibility associated with the ISEcp-1 tnpA-bla_CMY-2-blc-sugE element is regulated positively by ISEcp-1 tnpA and SugE and negatively regulated by Blc and unknown species-dependent host factor(s).

中文翻译：

---

沙门氏菌和志贺氏菌中的遗传分析和质粒介导的 blaCMY-2 以及由 ISEcp-1 tnpA-blaCMY-2-blc-sugE 调节的头孢曲松敏感性

背景

非伤寒沙门氏菌和志贺氏菌可引起人类肠胃炎。头孢曲松 (CRO) 已被用于治疗其感染，但是，CRO 耐药性的发展通常与质粒介导的bla _{CMY 相关。}在这里，我们研究了质粒介导的 IS Ecp-1 tnpA-bla _CMY-2 -blc-sugE 的存在以及这些基因在调节不同宿主 CRO 易感性中的作用。

方法

对 194 株沙门氏菌血清型和志贺氏菌进行了 CRO 敏感性测试。通过 PCR 扩增、Southern 印迹和 DNA 测序检查非易感菌株的质粒介导的 IS Ecp-1 tnpA-bla _CMY-2 -blc-sugE。质粒图谱由Hin dIII 消化的限制性片段长度多态性 (RFLP) 确定。四个重组质粒与来自不同基因IS ECP-1 TNPA-BLA _CMY-2 - BLC-菅构建，然后被转移到大肠杆菌和不同的沙门氏菌血清变型，以评估CRO易感性。

结果

在具有质粒介导的bla _{CMY-2 的}20 个 CRO 不敏感的霍乱沙门氏菌(5)、S. Typhimurium (4)、S. Mons (1)、S. Stanley (2) 和Shigella Sonnei (8)分离株中_，有19 个分离株携带 IS Ecp-1 tnpA - bla _CMY-2 - blc-sugE并且只有一种分离物带有tnpA-bla _CMY-2。将这些质粒转化到大肠杆菌pir116 中会产生多药耐药性。此外，PCR-RFLP 分析确定了 5 种不同的质粒谱和S之间相同的 RFLP 模式。鼠伤寒和S. 宋内。将重组质粒转化到大肠杆菌和不同的沙门氏菌血清型中，会产生从易感到抗性（尤其是诱导抗性）到依赖于基因和宿主的 CRO 的表型。

结论

与 IS Ecp-1 tnpA-bla _CMY-2 -blc-sugE元件相关的 CRO 易感性受 IS Ecp- 1 tnpA和 SugE 正向调节，并受 Blc 和未知物种依赖性宿主因子负向调节。