Characterisation of chromosomally-located blaCTX-M and its surrounding sequence in CTX-M-type extended-spectrum β-lactamase-producing Escherichia coli isolates
Characterisation of chromosomally-located blaCTX-M and its surrounding sequence in CTX-M-type extended-spectrum β-lactamase-producing Escherichia coli isolates
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DOI：
10.1016/j.jgar.2018.11.006
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发表时间：
2019-06-01
影响因子：
4.6
通讯作者：
Hirai, Itaru
中科院分区：
文献类型：
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作者：
Hamamoto, Kouta;Hirai, Itaru
目的：虽然人们认为CTX-M型超广谱β-内酰胺酶（ESBL）基因bla（CTX-M）主要由耐药质粒携带，但之前的研究也报道过具有染色体定位bla（CTX-M）的大肠杆菌。本研究旨在表征日本医院分离的产ESBL大肠杆菌中位于染色体上的bla（CTX-M）转座单元及其周围序列的遗传结构。方法：总共对81个产ESBL大肠杆菌分离株进行了研究。通过 S1 核酸酶消化的脉冲场凝胶电泳 (PFGE) 和 Southern 印迹杂交以及 PCR 扩增 DNA 片段的测序分析证实了染色体定位的 bla(CTX-M) 的存在。结果：在 81 株大肠杆菌分离株中的 22 株 (27.2%) 中证实了染色体定位的 bla(CTX-M) 检查；分别确定了染色体定位的 bla(CTX-M-14) 和 bla(CTX-M-15) 的五种和四种位置类型。在 22 个大肠杆菌分离株中，15 个（68.2%）具有单个染色体定位的 bla(CTX-M) 基因，可能是由于质粒 bla(CTX-M) 到染色体的单次转座所致。在分离株 N0057 中，bla(CTX-M-15) 转座单位从质粒转移到两个不同的染色体区域。此外，在分离株 N0211、N0214、N01127、N1682 和 N1753 中观察到已存在的染色体定位 bla(CTX-M-14) 到另一个染色体区域的“反复”转座；因此，这些分离株拥有两个染色体定位的 bla(CTX-M-14) 拷贝。结论：根据 PFGE，考虑到发生“反复”转座事件的分离株 N0211、N0214、N01127、N1682 和 N1753 具有遗传相关性，这些数据表明 bla(CTX-M) 在染色体上积累的可能性 CTX-M型产ESBL大肠杆菌。 (C) 2019 年国际抗菌化疗协会。由爱思唯尔有限公司出版。保留所有权利。
Objectives: Although it has been regarded that the CTX-M-type extended-spectrum beta-lactamase (ESBL) gene bla(CTX-M) is mainly carried by antimicrobial resistance plasmids, Escherichia coli possessing chromosomally-located bla(CTX-M) has been reported in previous studies. This study aimed to characterise the genetic structure of the chromosomally-located bla(CTX-M) transposition unit and its surrounding sequence in ESBL-producing E. coli isolated in a Japanese hospital.Methods: A total of 81 ESBL-producing E. coli isolates were studied. The existence of chromosomally-located bla(CTX-M) was confirmed by S1 nuclease-digested pulsed-field gel electrophoresis (PFGE) and Southern blot hybridisation and by sequencing analysis of the PCR-amplified DNA fragments.Results: Chromosomally-located bla(CTX-M) was confirmed in 22 (27.2%) of the 81 E. coli isolates examined; five and four location types of chromosomally-located bla(CTX-M-14) and bla(CTX-M-15) were determined, respectively. Among the 22 E. coli isolates, 15 (68.2%) possessed single chromosomally-located bla(CTX-M) gene, probably due to single transposition of a plasmidic bla(CTX-M) to the chromosome. In isolate N0057, the bla(CTX-M-15) transposition unit was transferred from a plasmid into two different chromosomal regions. In addition, 'recurrent' transposition of already existing chromosomally-located bla(CTX-M-14) to another chromosomal region was observed in isolates N0211, N0214, N01127, N1682 and N1753; consequently, these isolates possessed two copies of chromosomally-located bla(CTX-M-14).Conclusion: Considering that isolates N0211, N0214, N01127, N1682 and N1753 in which the 'recurrent' transposition event occurred were genetically related according to PFGE, these data suggest the possibility of accumulation of bla(CTX-M) on the chromosome in CTX-M-type ESBL-producing E. coli. (C) 2019 International Society for Antimicrobial Chemotherapy. Published by Elsevier Ltd. All rights reserved.