Identification of high risk lineages that contain Stx2 high producing strains in enterohaemorrhagic Escherichia coli

2015 Fiscal Year Final Research Report

• Project/Area Number: 25460542
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Bacteriology (including mycology)
• Research Institution: Kyushu University (2015); University of Miyazaki (2013-2014)
• Principal Investigator: Yoshitoshi Ogura 九州大学, 医学(系)研究科(研究院), 准教授 (40363585)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 腸管出血性大腸菌 / 志賀毒素 / O157 / ファージ

Outline of Final Research Achievements

Enterohemorrhagic E. coli (EHEC) causes diarrhea and hemorrhagic colitis with life-threatening complications, such as hemolytic uremic syndrome. Their major virulence factor is Shiga toxin (Stx), which is encoded by bacteriophages. Of the two types of Stx, the production of Stx2, particularly that of Stx2a (a subtype of Stx2), is a major risk factor for severe EHEC infections, but the Stx2 production level is highly variable between strains. Here, we define four major subtypes of Stx2a-encoding phages according to their genomic structure. The subtypes are correlated with Stx2a titers produced by the host O157 strains, suggesting a critical role of the phage subtype in determining the Stx2a production level. To identify high risk EHEC lineage, we performed genome sequence, high-resolution phylogenetic analysis and determination of Stx2 production of 300, 50, and 50 strains of O157, O145 and O121, respectively. By this analysis, we identified 3 high risk O157 lineages.

Free Research Field

細菌学