担当区分：筆頭著者   記述言語：英語   掲載種別：学位論文（博士）   出版者・発行元：Microbial Genomics  

Among the nine clades of Shiga toxin (Stx)-producing Escherichia coli O157:H7, clade 8 is thought to be highly pathogenic, as it causes severe disease more often than other clades. Two subclades have been proposed, but there are conflicting reports on intersubclade differences in Stx2 levels, although Stx2 production is a risk factor for severe disease development. The global population structure of clade 8 has also yet to be fully elucidated. Here, we present genome analyses of a global clade 8 strain set (n=510), including 147 Japanese strains sequenced in this study. The complete genome sequences of 18 of the 147 strains were determined to perform detailed clade-wide genome analyses together with 17 publicly available closed genomes. Intra-clade variations in Stx2 production level and disease severity were also re-evaluated within the phylogenetic context. Based on phylogenomic analysis, clade 8 was divided into four lineages corresponding to the previously proposed SNP genotypes (SGs): SG8_30, SG8_31A, SG8_31B and SG8_32. SG8_30 and the common ancestor of the other SGs were first separated, with SG8_31A and SG8_31B emerging from the latter and SG8_32 emerging from SG8_31B. Comparison of 35 closed genomes revealed the overall structure of chromosomes and pO157 virulence plasmids and the prophage contents to be well conserved. However, Stx2a phages exhibit notable genomic diversity, even though all are integrated into the argW locus, indicating that subtype changes in Stx2a phage occurred from the γ subtype to its variant (γ_v1) in SG8_31A and from γ to δ in SG8_31B and SG8_32 via replacement of parts or almost entire phage genomes, respectively. We further show that SG8_30 strains (all carrying γ Stx2a phages) produce significantly higher levels of Stx2 and cause severe disease more frequently than SG8_32 strains (all carrying δ Stx2a phages). Clear conclusions on SG8_31A and SG8_31B cannot be made due to the small number of strains available, but as SG8_31A (carrying γ_v1 Stx2a phages) contains strains that produce much more Stx2 than SG8_30 strains, attention should also be paid to this SG.

DOI： 10.1099/mgen.0.000935

Web of Science

Scopus

PubMed

記述言語：日本語   出版者・発行元：(公社)日本小児科学会  

症例は3歳男児で、発熱、腹痛を主訴とした。血液検査で高度炎症反応を認め、体幹・会陰・臀部の多形紅斑様の環状紅斑、白色下痢を生じた。咽頭アデノウイルス抗原陽性で、アデノウイルス咽頭炎に伴う多形滲出性紅斑、腸炎の診断で対症療法を行い発疹・下痢は改善した。その後、40度の発熱の継続、両側眼球結膜充血、腹部膨満、黄疸を生じ、腹部超音波で著明な胆嚢腫大を認めた。抗菌薬静注は効果がなく、口唇紅潮・四肢末端の変化が顕在化したことより、第8病日に川崎病の診断に至った。アスピリン内服、免疫グロブリン大量静注療法により症状は軽快した。発症1ヵ月時点で胆嚢が縮小し、発症2ヵ月時点で冠動脈病変は認めない。川崎病において著明な胆嚢腫大をきたすことは稀で、アデノウイルス感染症の主要症状と類似しているため診断までに時間がかかった。

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語  

担当区分：筆頭著者   記述言語：日本語  

記述言語：日本語  

記述言語：日本語  

記述言語：日本語  

記述言語：日本語