PDF(Pubmed)
Abstract：
High level carbapenem and extensively drug resistant (XDR) Escherichia coli strain N7, which produces a variant of New Delhi metallo-β-lactamase (NDM-5), was isolated from the influent of the Jungnang wastewater treatment plant located on Han River, Seoul, South Korea. Phenotypic and genotypic resistances to carbapenem were tested using agar and broth dilution methods, and polymerase chain reaction. Whole-genome sequencing was performed to characterize the genetic structure of strain N7. E. coli strain N7, which harbors the bla NDM-5 gene, showed high level of carbapenem resistance at concentrations of doripenem (512 mg/L) and meropenem (256 mg/L), and XDR to 15 antibiotics. Based on the genomic sequence analysis, two plasmids, a hybrid IncHI2/N-type and an IncX3 type, were present. The former contains a cluster (bla NDM-5-ble MBL -trpF-dsbD) bracketed by multi-insertional sequences, IS3000, ISAba125, IS5, and IS26. The latter carries the following resistance genes: bla CTX-14, aac(3)-IV, aadA1, aadA2, aph(3\')-Ia, aph(4)-Ia, sul1, sul2, sul3, dfrA12, fosA3, oqxA, oqxB, mph(A), and floR, and cmlA1. The chromosome, contig3, and contig5 also carry bla CTX-64 and mdf(A), tet(A), and erm(B), tet(M) and aadA22, respectively. Strain N7 also harbors virulence factors such as fimH, flu, ecpABCDE, sfmA, hlyE, and gadA. This study demonstrates the emergence of high level carbapenem resistant XDR E. coli strain N7 containing bla NDM-5 in aquatic environment, Seoul, South Korea. Due to the presence of mobile genetic elements, this strain could horizontally transfer resistance genes, including bla NDM-5 to environmental bacteria. Thus, it is necessary to conduct continuous surveillance for carbapenem resistance in various aquatic environments.
摘要：
高水平的碳青霉烯和广泛耐药（XDR）大肠杆菌菌株N7，产生新德里金属β-内酰胺酶（NDM-5）的变体，从位于汉江的准南污水处理厂的进水中分离出来，首尔,韩国。使用琼脂和肉汤稀释方法测试了对碳青霉烯的表型和基因型抗性，和聚合酶链反应。进行全基因组测序以表征菌株N7的遗传结构。大肠杆菌菌株N7，含有blaNDM-5基因，在多尼培南（512mg/L）和美罗培南（256mg/L）的浓度下显示出高水平的碳青霉烯抗性，和XDR对15种抗生素。基于基因组序列分析,两个质粒,混合IncHI2/N型和IncX3型，在场。前者包含一个簇（blaNDM-5-bleMBL-trpF-dsbD），由多个插入序列组成，IS3000、ISAba125、IS5和IS26。后者携带以下抗性基因：blaCTX-14，aac（3）-IV，aadA1,aadA2,aph(3')-Ia,aph(4)-Ia,sul1,sul2,sul3,dfrA12,fosA3,oqxA,OQXB,mph(A),和floR,和cmlA1。染色体，重叠群3，重叠群5也携带blaCTX-64和mdf(A)，tet(A),和erm(B)，tet(M)和aadA22。N7菌株还含有毒力因子，如fimH，流感,ecpABCDE,sfmA,hlyE,和gada。这项研究表明，在水生环境中出现了含有blaNDM-5的高水平碳青霉烯抗性XDR大肠杆菌N7菌株，首尔,韩国。由于移动遗传元件的存在，这种菌株可以水平转移抗性基因，包括BLANDM-5对环境细菌。因此，有必要对各种水生环境中的碳青霉烯耐药性进行连续监测。
