牦牛携带的产志贺毒素大肠杆菌分离株的多位点序列分型研究

目的 对牦牛携带的产志贺毒素大肠杆菌(Shiga toxin-producing Escherichia coli,STEC)进行多位点序列分型(Multilocus sequence typing,MLST)分析,了解菌株的遗传进化关系及致病潜力。方法 根据E. coli MLST数据库(http://mlst.ucc.ie/mlst/dbs/Ecoli)提供的MLST方案,对青海玉树牦牛中分离的54株STEC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及菌株序列型(Sequence type,ST),并使用BioNumerics软件构建最小生成树(Minimum spanning tree,MST),分析牦牛ST型与HUSEC及人源主要流行血清群STEC菌株ST型间的进化关系。结果 54株牦牛STEC菌株呈现高度遗传多态性,可分为31个ST型别,其中包括7个新的等位基因型和17个新的ST型,并存在与HUSEC及主要流行血清群STEC亲缘关系相同或相近的ST型别。结论 青藏高原牦牛携带的STEC具有遗传多样性及一定的特异性,部分菌株具有对人致病的潜力。

Multilocus sequence typing of Shiga toxin-producing Escherichia coli isolated from yaks

To investigate the molecular epidemiologic characteristics and the potential cause for human disease of Shiga toxin-producing Escherichia coli （STEC） isolated from yaks in the Qinghai-Tibetan Plateau, a multilocus sequence typing （MLST） scheme provided by E. coli MLST database （http：//mlst. ucc. ie/mlst/dbs/Ecoli） was performed. Seven housekeep- ing genes were amplified by PCR and then sequenced. The sequence types （STs） were determined by sequences comparing. The minimum spanning tree （MST） was constructed using BioNumerics software. Thirty-one STs including 7 new alleles and 17 new STs were identified in 54 yak STEC isolates. Some of these STs shared the same or related STs with HUSEC or human STEC strains. It could be concluded that there exists highly molecular diversity among the STEC isolates in yaks, some of which may have the potential to cause human disease.