Identification of novel pathotypes of diarrheal Escherichia coli by analyzing clinical isolates in which representative virulence genes for known pathotypes were not detected.

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K21527
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 49:Pathology, infection/immunology, and related fields
• Research Institution: Kurume University
• Principal Investigator: Ogura Yoshitoshi 久留米大学, 医学部, 教授 (40363585)
• Project Period (FY): 2020-07-30 – 2023-03-31
• Keywords: 大腸菌 / 下痢症 / ゲノム / 疫学

Outline of Final Research Achievements

In this study, we investigated 13 cases of diarrhea outbreaks suspected to be caused by Escherichia coli carrying unknown virulence factor that occurred in the past in four prefectures. As a result of determining the genome sequence, serotyping, sequence typing, and phylogenetic analysis of 149 E. coli strains isolated in these cases, E.coli was presumed to be the causative agent of the outbreak in 7 cases. The strains in each case were classified into different serotypes, and genes showing high homology to known virulence factors were also detected in some strains. In the future, it will be necessary to perform genome comparisons with commensal E. coli from healthy carriers and larger-scale analyzes using many cases.

Free Research Field

細菌学

Academic Significance and Societal Importance of the Research Achievements

各都道府県では、年間数件から数十件程度、病原因子不明の大腸菌が原因と疑われる下痢症事例が発生している。集団発生で複数の患者から同一血清型の大腸菌が分離されるなど、原因菌として強く疑われる事例も少なくない。そのため、まだ知られていない新規の病原因子を保有する新型の病原性大腸菌が存在すると考えられる。原因菌の同定は、原因食材の特定や感染ルートの推定に必須であり、今後の感染防止対策にも重要な情報となる。本研究で得られる成果は、感染性下痢症の臨床検査や疫学調査などに大きく貢献できると期待される。