福建省福氏志贺菌4c亚型的分子特征分析

摘要

Shigella species remain the leading bacterial etiological agents of gastrointestinal diseases worldwide . To investigate virulence gene distribution , genetic relationship and genomic diversity of S. flexneri 4C strains from Fujian Province , four virulence genes ipaH ,setl(.setlA and setlB) ,sen and ial were detected by PCR for 17 S. flexneri 4C isolates . Molecular typing of these strains was performed with pnlsed-field gel electrophoresis(PFGE) .It was revealed that positive rates for the ipaH, setlCsetlA and setlB ) ,sen and ial gene were l00% ,94 . 12% , 82 .35% and 88 .23% , respectively . Four distribution modes of virulence genes were observed in the 17 strains , while 76 .47% belonged to type I, the dominant mode . Twelve PFGE patterns (P1-P12) were detected according to l00% identity , and no clustered or dominant pattern was observed . However , three PFGE groups (G1-G3) were identified based on the TENOVER principle , among which Group 1 of 64 .71% was the dominant . These results indicated that most S. flexneri 4C strains in Fujian were virulent . The fact that no obvious transmission chain was observed among most patients , whereas the clustering tendency of diverse circulating clones occurred , suggesting that certain clones of S. flexneri 4C might gradually develop as the main and stable S. flexneri strains in Fujian .%目的 分析福建省新出现的福氏志贺菌4c血清亚型的毒力基因分布,菌株间的遗传关联度以及基因组的多态性.方法 运用PCR扩增技术对17株F4c菌进行ipaH、set1(set1A和set1B)、sen、ial 4种毒力基因的检测,同时运用脉冲肠凝胶电泳(PFGE)技术进行分子分型.结果 ipaH、set1(set1A和set1B)、sen 、ial基因阳性的菌株分别占100%、94.12%、 82.35%、88.23%; 17株F4c菌分为I-IV型不同的毒力基因分布模式, I型是优势模式占76.47%;按100%的相似度,PFGE有12种型别(P1-P12),不存在集中优势的PFGE型别;根据TENOVER原则,分为3个PFGE群(G1-G3),G1是优势群,占64.71%.结论 我省分离的F4c血清亚型的志贺菌大部分菌株具有较强的毒力特征;绝大多数感染患者之间无明显的传播关系,不同克隆群在传播中存在着集中趋势,提示某一克隆群的F4c菌有可能逐步演变成为我省主要且稳定的福氏志贺菌流行菌株.