To investigate NDM-1-producing atypical Enteroaggregative Escherichia coli (aEAEC) of sequence type 349 from hospitalized patients, the isolates 13ZX28 and 13ZX36 were subjected to antimicrobial susceptibility testing, conjugation and whole genome sequencing. Only one single nucleotide mutation was detected in chromosomes despite different plasmid profiles. Both isolates were positive for bla_NDM-1 mediating resistance to carbapenem. A novel plasmid p13ZX28–272 (~272-kb) from 13ZX28 encodes bla_NDM-1. Interestingly, its sequence was identical to the two plasmids p13ZX36–200 (~200-kb) and p13ZX36–70 (~70-kb) from 13ZX36. Formation of the former episome possibly involved homologous recombination through a 4948-bp large fragment located on each of the two latter plasmids. Furthermore, plasmid p13ZX28–272 could be resolved into a ~ 98-kb daughter plasmid by IS26 rearrangement following conjugation. The plasticity of the plasmids is recognized, which warrants further investigation to evaluate the underlying public health risk and understand how antibiotic selection pressure drives this process.

为了研究来自住院患者的序列类型 349 的NDM-1 非典型肠聚集性大肠杆菌(aEAEC)，对分离株 13ZX28 和 13ZX36 进行了抗菌药敏试验、结合和全基因组测序。尽管质粒谱不同，但在染色体中仅检测到一个单核苷酸突变。两种分离株均呈bla _NDM-1阳性，介导碳青霉烯类耐药。来自 13ZX28 的新型质粒 p13ZX28–272 (~272-kb) 编码bla _NDM-1. 有趣的是，它的序列与来自 13ZX36 的两个质粒 p13ZX36-200 (~200-kb) 和 p13ZX36-70 (~70-kb) 相同。前一种附加体的形成可能涉及通过位于后两种质粒中的每一种上的 4948 bp 大片段进行的同源重组。此外，通过结合后的 IS 26重排，质粒 p13ZX28-272 可以分解为约 98-kb 的子质粒。质粒的可塑性得到认可，这需要进一步调查以评估潜在的公共卫生风险并了解抗生素选择压力如何推动这一过程。