福建省非典型肠致病性大肠埃希菌的分子特征研究

摘要：目的　研究福建省非典型肠致病性大肠埃希菌（ａＥＰＥＣ）菌株的毒力基因特征和菌株间的遗传相似
度；结合菌株的背景资料分析不同的分子特征对ａＥＰＥＣ 流行的影响。方法　运用ＰＣＲ 技术进行系列的相
关毒力基因扩增；同时运用脉冲场凝胶电泳分子分型技术，对福建省２０１０－２０１２年分离的ａＥＰＥＣ 菌株进
行脉冲场凝胶电泳（ＰＦＧＥ）分子分型。结果　分离３０株实验菌株毒力基因的检测呈阳性的分别为：犫１１２１
５３．３％ （１６），狔犻犪犃３６．７％ （１１），狊犲狋／犲狀狋、狀犾犲犅、狀犾犲犈均为３０％ （９），犾狆犳犃犚１４１２３．３％ （７），犲犳犪／犾犻犳犃
２０％ （６），犲犺狓犃３．３３％ （１）；其余毒力基因均未检出；９３．３％ （２８）菌株不同程度地携带有相关的毒力因
子。２９株菌按照１００％的相似度分为１５个ＰＦＧＥ 型别（Ｐ１ Ｐ１５）；其中存在４组不同的ＰＦＧＥ 簇（Ｉ Ⅳ），
相同ＰＦＧＥ 簇的病例在发病的时间和地区上有聚集性，同时相同簇内菌株的毒力基因谱也表现相同。结论
　犫１１２１、狔犻犪犃和ＥＨＥＣ 毒力岛ＯＩ １２２ 相关基因（犲犳犪１／犾犻犳犃，狀犾犲犅，狀犾犲犈，狊犲狋／犲狀狋） 在福建省ａＥＰＥＣ 菌
株中携带率较高。非典型肠致病性大肠埃希菌的毒力谱表现为多样性， 基因组也呈现遗传多态性；同时
ＰＦＧＥ 分析发现福建省存在由ａＥＰＥＣ 新发病原菌引起的聚集性病例。
关键词：非典型肠致病性大肠埃希菌；毒力基因；ＰＦＧＥ
中图分类号：Ｒ３７８　　文献标识码：Ａ　　文章编号：１００９ ６６３９ （２０１４）０３ ０２１６ ０５
犕狅犾犲犮狌犾犪狉犮犺犪狉犪犮狋犲狉犻狊狋犻犮狊狅犳犪狋狔狆犻犮犪犾犲狀狋犲狉狅狆犪狋犺狅犵犲狀犻犮

Molecular characteristics of atypical enteropathogenic E.coli isolated in Fujian

Objective To analyze the molecular characteristics of atypical enteropathogenic Escherichia coli（aEPEC）isolated in Fujian,including the analysis of virulence genes and genetic relationship among different aEPEC isolates. Methods A total of 30aEPEC isolates were collected in Fujian from 2010to 2012.The virulence-related genes were amplified by PCR and their genetic relationships were determined by pulsed-field gel electrophoresis（PFGE）. Results Out of 15virulence genes,eight were amplified by PCR which were b1121（53.3%）,yiaA（36.7%）,set/ent（30%）,nleB（30%）,nleE（30%）,lpfAR141（23.3%）,efa/lifA（20%）and ehxA（3.33%）.93.3% of isolates harbored virulence-related genes.Fifteen PFGE patterns（P1-P15）were observed in 29strains according to 100%similarity,and were grouped in 4PFGE clusters（I-IV）.Cases within each cluster showed similar onset time and geographic origination,while strains within each cluster shared identical virulence-gene profiles. Conclusions Majority of atypical enteropathogenic E.coli strains isolated in Fujian harbor virulence-related genes,especially b1121,yiaA and other genes（efa1/lifA,nleB,nleE and set/ent）in the pathogenic island OI-122of EHEC.Meanwhile,aEPEC strains display considerable heterogeneity in virulence-gene profiles and genome structures.Some clustered cases with new aEPEC strains has been also identified in Fujian by PFGE.