Investigation of virulence factors based on whole genome data in Escherichia coli associated with foodborne disease outbreaks

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K18439
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Hygiene and public health; Bacteriology (including mycology)
• Research Institution: Osaka Institute of Public Health
• Principal Investigator: Harada Tetsuya 地方独立行政法人 大阪健康安全基盤研究所, 微生物部, 主任研究員 (70516723)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: Outbreak関連大腸菌 / 食中毒 / 下痢原性

Outline of Final Research Achievements

To investigate the virulence factors in Escherichia coli O166:H15 isolates from diarrhea patients in several foodborne outbreaks, whole genome analyses, suckling mouse assays, bacterial adherence assays, and contact-dependent hemolytic activity tests were performed with 5, 2, and 2 isolates from 5 outbreak patients, 2 sporadic patients, and 2 asymptomatic carriers, respectively. Multilocus sequence typing revealed that the 8 isolates, except for one from an asymptomatic carrier, belonged to ST349 and a single locus variant of ST349. Core genome single nucleotide polymorphism-based analyses showed that the 8 isolates belonged to a single group. The four isolates from outbreak patients were positive for enteroaggregative E. coli heat-stable enterotoxin 1 gene and dispersin protein genes. In suckling mouse assays with a culture pellet of an outbreak isolate, fluid accumulation was observed. Additionally, several isolates from outbreak patients showed diffuse adherence to HeLa cells.

Free Research Field

食品微生物

Academic Significance and Societal Importance of the Research Achievements

複数の原因不明食中毒事例に共通して分離されるOutbreak関連大腸菌O166:H15について、供試株5株が異なるクローンでありながら単一系統群に属することが示された。本成果は、共通する病原因子の存在を示唆する可能性が高く、その公衆衛生学的意義は高い。また、2016年から2019年にも本菌が分離される集団食中毒事例が相次いで報告され、報道発表により社会的注目を集めた大規模事例もみられた。それゆえ、本菌への関心度は今後ますます高まることが予想されることから、本成果を基礎データとして病原性の解明が進むことが期待できる。