蒙古产超广谱β-内酰胺酶的大肠杆菌和克雷伯菌属分离株的分子特征。
Molecular characterization of extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella spp. isolates in Mongolia.
机构信息
Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
Department of Cellular Biology and Biochemistry, Mongolian National University of Medical Sciences, Mongolia.
出版信息
J Microbiol Immunol Infect. 2016 Oct;49(5):692-700. doi: 10.1016/j.jmii.2015.05.009. Epub 2015 Jun 27.
BACKGROUND/PURPOSE: The aim of this study was to determine the molecular characteristics of β-lactamase genes in extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae isolates from Mongolia.
METHODS
Fifty-six ESBL-producing Enterobacteriaceae isolates were collected, of which 46 were Escherichia coli, seven were Klebsiella pneumoniae, and three were K. oxytoca. Minimum inhibitory concentrations for selected antibiotics were tested using the agar dilution method, and the β-lactamase genes were determined using polymerase chain reaction combined with sequencing. Pulsed-field gel electrophoresis (PFGE) was used for genotyping all isolates, and phylogenetic grouping was performed on ESBL-producing E. coli isolates. Conjugation tests combined with plasmid digestion assays were used to determine whether there was a horizontal spread in Mongolia.
RESULTS
Among the 56 ESBL-producing isolates, 43 isolates (76.8%) were resistant to fluoroquinolones, but all isolates were susceptible to carbapenems and amikacin. The polymerase chain reaction sequencing results showed that the dominant CTX-M genotype was CTX-M-15 (19/46, 41.3%) in the ESBL-producing E. coli isolates. By contrast, CTX-M-14 and CTX-M-3 were the major genotypes found in Klebsiella spp. Phylogenetic analysis revealed that 21 ESBL-producing E. coli isolates belonged to group D (21/46, 45.6%), followed by group A (13/46, 28.3%), group B2 (11/46, 23.9%), and group B1 (1/46, 2.2%). Only four E. coli isolates (4/46, 8.7%) belonged to the ST131 clone. PFGE showed that the ESBL-producing Enterobacteriaceae were genetically unrelated. The conjugation assay showed that two plasmids harboring CTX-M-15 in E. coli isolates were genetic unrelated, whereas seven plasmids harboring CTX-M-14 (5/7 and 2/7) and four plasmids harboring CTX-M-55 (4/4) showed genetic relatedness, indicating the dissemination of resistance plasmids in this area.
背景/目的：本研究旨在确定蒙古产超广谱β-内酰胺酶（ESBL）肠杆菌科分离株β-内酰胺酶基因的分子特征。
方法
收集了 56 株产 ESBL 肠杆菌科分离株，其中 46 株为大肠埃希菌，7 株为肺炎克雷伯菌，3 株为产酸克雷伯菌。采用琼脂稀释法测定所选抗生素的最低抑菌浓度，采用聚合酶链反应结合测序法测定β-内酰胺酶基因。对所有分离株进行脉冲场凝胶电泳（PFGE）基因分型，对产 ESBL 大肠埃希菌分离株进行进化群分组。结合质粒消化试验进行接合试验，以确定蒙古是否存在水平传播。
结果
在 56 株产 ESBL 分离株中，43 株（76.8%）对氟喹诺酮类药物耐药，但所有分离株对碳青霉烯类和阿米卡星敏感。聚合酶链反应测序结果显示，产 ESBL 大肠埃希菌分离株中 CTX-M-15 型（19/46，41.3%）为优势 CTX-M 基因型。相比之下，CTX-M-14 和 CTX-M-3 是肺炎克雷伯菌的主要基因型。系统进化分析显示，21 株产 ESBL 大肠埃希菌分离株属于 D 组（21/46，45.6%），其次是 A 组（13/46，28.3%）、B2 组（11/46，23.9%）和 B1 组（1/46，2.2%）。只有 4 株大肠埃希菌分离株（4/46，8.7%）属于 ST131 克隆。PFGE 显示产 ESBL 肠杆菌科在遗传上无相关性。接合试验显示，携带 CTX-M-15 的大肠埃希菌分离株的 2 个质粒遗传上无相关性，而携带 CTX-M-14（5/7 和 2/7）的 7 个质粒和携带 CTX-M-55（4/4）的 4 个质粒遗传上具有相关性，表明该地区耐药质粒的传播。
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