福建省非典型肠致病性大肠杆菌(aEPEC)的发现及某些分子特征的研究

Identification and preliminary molecular characterization of an atypical enteropathogenic Escherichia coli strain from Fujian

目的 2010年10月从一名死婴粪便标本中分离到非典型肠致病性大肠杆菌(aEPEC),为福建省首次鉴定该病原菌。本研究的目的是了解该病原菌的特征,为进一步开展aEPEC的研究工作提供基础数据。方法包括常规的系统生化鉴定、血清学鉴定、药敏试验、PCR检测毒力基因分布、eaeA基因的测序分析。结果该菌株生化表现符合大肠埃希氏菌特征;现有的典型的EPEC血清型不能凝集;药敏实验结果提示对大部分的药物均敏感;毒力基因检测为eaeA+、bfp-、stx1-s、tx2-、ehxA-、paa-;eaeA序列在NCBI上比对的结果均提示为大肠埃希氏菌(EHEC/EPEC)紧密素(intimin)的eaeA基因。结论根据常规实验、分子诊断及测序结果证实该病原菌为福建省首次鉴定的非典型肠致病性大肠杆菌(aEPEC),同时我们需要进一步检测其它的毒力相关基因,探讨这些基因和该菌株致病力的关系。

An atypical enteropathogenic Escherichia coli（aEPEC） strain,firstly documented in Fujian,was isolated from a fecal specimen of a fatal infant case in October,2010.The purpose of this study was to investigate characterization of this pathogenic strain,facilitating further research on aEPEC.A variety of assays were performed,including routine systematic biochemical identification,serotyping,antibiotics sensitivity tests,PCR amplification of virulent genes,and sequence analysis of eaeA gene.Biochemical characterization indicated this isolate was Escherichia coli,not agglutinating with typical EPEC antisera available.Antibiotic resistance tests showed susceptible to most drugs;PCR detection of virulent genes revealed eaeA＋,bfp-,stx1-,stx2-,ehxA-,paa-;BLAST results of partial sequenced eaeA gene indicated identical to the eae gene for intimin of Escherichia coli EHEC and EPEC.Therefore,routine biochemical assays,molecular diagnosis and sequence analysis confirmed this strain was the first identified aEPEC isolate in Fujian,and extensive investigation should be conducted to survey its virulence-associated genes and address virulent markers of aEPEC isolates.