非O157产志贺毒素大肠杆菌分离株的多位点序列分型研究

目的 对国内部分地区非O157产志贺毒素大肠杆菌分离株进行分子分型分析，了解菌株间的遗传进化关系。 方法 根据mlst.ucc.ie数据库提供的大肠杆菌多位点序列分型（Multilocus Sequence Typing, MLST）方案，对来自我国河南、黑龙江2省的29株产志贺毒素大肠杆菌分离株的7个管家基因进行PCR扩增并测序，通过序列比对确定其等位基因谱及菌株序列型（Sequence type, ST），使用MEGA、eBURST生物信息软件分析不同ST序列群及菌株间的进化关系。结果 29株非O157产志贺毒素大肠杆菌呈现较大的遗传多态性，可分为13个ST型别，其中ST155为优势型别（34.48%）。同时研究发现2个新等位基因型（fumC376、recA214）和3个新序列型（ST2460、ST2467、ST2468）。结论 29株非O157产志贺毒素大肠杆菌菌株之间具有分子多态性，与国际流行菌株具有一定的亲缘关系。加强我国对这一类菌株的检测和监测具有重要的公共卫生意义。

Multilocus sequence typing of non-O157 Shiga Toxin-Producing Escherichia coli isolates

To investigate the molecular epidemiologic characteristics of non-O157 Shiga toxin-producing Escherichia coli isolates collected from some locations of China over a period of time, a multilocus sequence typing (MLST) scheme provided by Escherichia coli MLST database was performed. Seven housekeeping genes were amplified by PCR and then sequenced. The sequence types (STs) were determined by sequences comparing. The MEGA and eBURST softwares were used for phylogenetic analysis. MLST analysis showed that there were 13 STs identified in 29 isolates, including 3 new STs named ST2460，ST2467 and ST2468. The predominant sequence type was ST155, which consisted of 10 isolates (34.48%), followed by ST906 (17.24%), ST446 (10.44%) and ST33 (6.90%), the other 9 STs consisted of only one isolate. It can be concluded that there exists molecular diversity among the non-O157 Shiga toxin-producing Escherichia coli isolates, which showed genetic relationship with the popular strains worldwide. The detection and surveillance of this kind of isolates is important to public health.