Department of Food Science & Technology, School of Agriculture and Biology, State Key Lab of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, China.
Laboratory of Microbiology, Shanghai Municipal Center for Disease Control and Prevention, Shanghai, China.
Zoonoses Public Health. 2021 Nov;68(7):760-768. doi: 10.1111/zph.12825. Epub 2021 Jun 4.
Multidrug-resistant Salmonella Enteritidis (S. Enteritidis) isolates have become a significant threat to public health, and fosfomycin has been proposed as one of the therapeutic antibiotics for serious infections by resistant pathogens. In this study, a total of 501 clinical S. Enteritidis isolates were screened and 14 (2.8%) isolates exhibited resistance to fosfomycin (MIC ≥ 1,024 μg/mL) as well as ceftriaxone (MIC ≥ 128 μg/mL). The fosA3 gene was identified in these 14 isolates. The fosA3 gene that co-transferred with bla was observed on the IncFII plasmids with sizes of ~ 78 (n = 7) or ~ 111 (n = 2) kbp in 9 transconjugants. The fosA3-bearing plasmid p12367A is 111,764 bp in length and possessed a typical IncFII backbone. A 7.6-kbp multidrug resistance region (MRR) was identified in p12367A, which was comprised of fosA3 and bla genes interspersed with ΔISEcp1 and three copies of IS26. Two typical antibiotic resistance determinants (IS26-orf3-orf2-orf1-fosA3-IS26 and IS26-orf477-bla -ΔISEcp1-IS26) shared one IS26 in the MRR. The genetic arrangement of the MRR may have resulted from the stepwise integration of IS26 mobile elements via homologous recombination. Horizontal transfer of IncFII plasmids might contribute to the dissemination of fosA3 and bla resistance genes in S. Enteritidis interspecies. These findings underline further challenges for the prevention and treatment of Enterobacteriaceae infections posed by epidemic IncFII plasmids bearing fosA3-bla .
501 株临床分离的肠炎沙门氏菌（S. Enteritidis）进行了筛选，其中 14 株（2.8%）对磷霉素（MIC≥1024μg/mL）和头孢曲松（MIC≥128μg/mL）表现出耐药性。在这 14 株分离株中鉴定出了 fosA3 基因。在 9 个转导子中，观察到与 bla 共转移的 fosA3 基因位于 IncFII 质粒上，大小约为 78（n=7）或 111（n=2）kbp。携带 fosA3 的质粒 p12367A 长 111764bp，具有典型的 IncFII 骨架。在 p12367A 中鉴定出一个 7.6kbp 的多药耐药区（MRR），该区域由 fosA3 和 bla 基因组成，其间散布着 ΔISEcp1 和三个 IS26 拷贝。p12367A 中的两个典型抗生素耐药决定簇（IS26-orf3-orf2-orf1-fosA3-IS26 和 IS26-orf477-bla-ΔISEcp1-IS26）在 MRR 中共享一个 IS26。MRR 的遗传排列可能是通过同源重组逐步整合 IS26 移动元件所致。IncFII 质粒的水平转移可能导致 fosA3 和 bla 耐药基因在肠炎沙门氏菌种间的传播。这些发现进一步强调了携带 fosA3-bla 的流行 IncFII 质粒对肠杆菌科感染的预防和治疗带来的挑战。
