天津地区志贺菌志贺肠毒素基因分布与脉冲场凝胶电泳分型研究

Distribution of Shigella Enterotoxins Genes and PFGE Molecular Typing of Shigella Strains in Tianjin

目的了解天津地区志贺菌流行株的志贺肠毒素基因分布和PFGE分子分型情况。方法采用PCR方法检测天津地区2005—2007年分离的62株志贺菌编码志贺肠毒素的基因(set1As、et1Bs、en),并用脉冲场凝胶电泳(PFGE)对菌株进行分子分型和聚类分析。结果 62株志贺菌中福氏志贺菌占58.06%,其中福氏2b为福氏志贺菌的优势型别;宋内志贺菌占41.94%;福氏志贺菌的三种志贺肠毒素基因检出率均明显高于宋内志贺菌(P<0.05);受试菌株的基因组DNA经PFGE分型,福氏志贺菌可分为10种带型(FⅠ～FⅩ);宋内志贺菌可分为4种带型(SⅠ～SⅣ),其中SⅠ型占86.96%(20/23株)。结论天津地区流行的志贺菌株编码肠毒素基因set1As、et1B和sen在不同血清群中的分布有显著性差异;宋内志贺菌可能源于亲缘关系很近的克隆系(SⅠ型),福氏志贺菌PFGE分子分型呈现出明显的多态性。

Objective To know the distribution of Shigella enterotoxins （ShET） genes, and the PFGE molecular typing of Shigella strains in Tianjin. Methods Three kinds of Shigella enterotoxin genes of 62 Shigella strains were detected by PCR; all strains were typed molecularly by pulsed field gel electrophoresis （PFGE）. Results There were 36 strains of Shigellaflexneri and 26 strains of Shigella sonnei within all Shigella strains; the positive rate of setlA, setlB and sen were, 40.32% （25/62）, 40.32% （25/62）and 50% （31/62）in order. There was significant difference of enterotoxin genes distribution between Shigellaflexneri and Shigella sonnei. All strains could be divided into 14 molecular types. Conclusion The prevalent Shigella strains in Tianjin were ShigeUa sonnei and Shigellaflexneri from the year 2005 to 2007. The rate of Shigella sonnei grows up sharply years. Shigella sonnei strains isolated in Tianjin show a close relationship from 2005 to 2007, while Shigellaflexneri comes from different clones.