State Key Laboratory of Respiratory Disease, First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510230, China.
The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China.
Sci Rep. 2017 Mar 24;7:44866. doi: 10.1038/srep44866.
To study molecular epidemiology of CTX-M-55-carrying Escherichia coli isolates from urinary tract infections (UTIs) in China. 111 bla-positive E.coli isolates from UTIs patients in China were studied. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) were used to analyze the homologies among the strains. Conjugation experiments, S1nuclease PFGE and PCR analysis were performed to characterize plasmids harboring bla and their genetic environment. 111 isolates were clustered into 86 individual pulsotypes and three clusters by PFGE. Fifty-five (49.5%) of the isolates belonged to 8 STs. Most of the ST1193 isolates belonged to one PFGE cluster. Transconjugants (n = 45) derived from randomly selected bla donors (n = 58), were found to contain a single 90-kb conjugative plasmid, which mainly belonged to the IncI1 groups (34, 76%). Among the IncI1 plasmids, the bla/IncI1/ST16 predominated (23/34, 68%). The bla and aac (3')-II genes were frequently detected on the IncI1 plasmids, and the insertion of ISEcp1 or IS26 was observed at the 48 bp or 45 bp upstream of the start codon of bla gene. The dissemination of bla gene among E. coli UTI isolates, appeared to be due to both the major clonal lineage of ST1193 and the horizontal transfer of epidemic plasmid IncI1/ST16.
研究中国尿路感染（UTI）患者中产 CTX-M-55 携带大肠埃希菌的分子流行病学。对中国 UTI 患者中 111 株bla阳性大肠埃希菌进行研究。采用脉冲场凝胶电泳（PFGE）和多位点序列分型（MLST）分析菌株之间的同源性。进行了接合实验、S1 核酸酶 PFGE 和 PCR 分析，以表征携带 bla 的质粒及其遗传环境。111 株分离株通过 PFGE 聚类为 86 个个体脉冲型和 3 个簇。55（49.5%）株分离株属于 8 个 ST。大多数 ST1193 分离株属于一个 PFGE 簇。从随机选择的 bla 供体（n=58）中获得的转导子（n=45）被发现含有单个 90-kb 可接合质粒，主要属于 IncI1 组（34，76%）。在 IncI1 质粒中，bla/IncI1/ST16 占主导地位（23/34，68%）。bla 和 aac（3'）-II 基因经常在 IncI1 质粒上检测到，并且在 bla 基因起始密码子上游的 48bp 或 45bp 处观察到 ISEcp1 或 IS26 的插入。bla 基因在大肠埃希菌 UTI 分离株中的传播似乎是由于 ST1193 的主要克隆谱系和流行质粒 IncI1/ST16 的水平转移。
