大肠杆菌O157∶H7 OI115岛的多态性分析

目的研究大肠杆菌O157∶H7测序菌株EDL933的OI115岛在肠杆菌科细菌中的分布。方法用PCR和杂交方法检测OI115岛的21个基因,同时进行该岛序列测定。结果OI115岛和SPI-1毒力岛的分布特点相似,具有种属局限性。仅在大肠杆菌中存在,在EPEC、ETEC、EAggEC均可检测到该岛的缺失形式,在沙门菌、志贺菌、耶尔森、摩根菌等其他肠杆菌科细菌中未发现该岛的存在。在不同类别的致泻性大肠杆菌中,OI115岛也各有特点,共检测到该岛的3种存在形式。产生志贺毒素的大肠杆菌O157∶H7菌株、2株EAggEC和2株不典型大肠杆菌均具有完整的OI115岛。在不产生志贺毒素的大肠杆菌O157中具有H5、H12、H29、H42、H11、H19、H26、H10、H21鞭毛型的菌株缺失了第3基因簇,具有H16鞭毛型的菌株第2、第3基因簇同时缺失。结论本研究发现,OI115岛在致泻性大肠杆菌中分布广泛,可能和病原菌的进化有关。

The phylogeny of OI115 island of Escherichia coli O157:H7

Objective To detect the prevalence of the E.coli O157 EDL933 strain's OI115 in Enter- obucteriaceae.Methods We analyzed the distribution of OI115 in Enterobacteriaceae with PCR and DNA hybrid- ization then sequenced the island.Results OI115 only present in pathogenic E.coli such as EPEC,ETEC,EA- ggEC;but not in other enteric bacteria such as Salmonella,Shigella,Morganella,Enterobacter,Citrobacter, Yersinia and others.Similarly,it has been known that the SPI-1 only present in Salmonella genus.In some iso- lates of diarrheagenic E.coli,OI115 was identified as three types.The intact OI115 was identified in all of the shiga-toxin producing E.coli O157:H7 isolates,some strains of EAggEC and some strains of atypical E.coli tested in this study.In 50 stx-negative E.coil O157 isolates tested,40 strains lost the third part of OI115 which possess flagella antigen of H5,H12,H29,H42,H11,H19,H26,H10,H21,5 isolates which possess flagella antigen of H16 lost both the second and the third part of the OI115 island.Conclusion The prevalence of OI115 in diar- rheagenic E.coli indicated its possible role in emerging of pathogenecity and evolution of E.coli.