Clinical characteristic and molecular epidemiology of high-risk clone Bacillus cereus ST1420

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K08853
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 54030:Infectious disease medicine-related
• Research Institution: National Institute of Infectious Diseases
• Principal Investigator: Suzuki Satowa 国立感染症研究所, 薬剤耐性研究センター, 室長 (30373400)
• Co-Investigator(Kenkyū-buntansha): 小林 彩香 帝京大学, 医学部, 講師 (30962873)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: Bacillus cereus / 院内感染 / 血流感染

Outline of Final Research Achievements

Bacillus cereus isolated from bloodstream infections (BSI) at several hospitals in Japan, includes a variety of ST types other than the presumed high-risk clone ST1420. Although isolates belonging to CereusIII in clade1, which are closely related to B. anthracis, are relatively observed more often in BSI cases, no significant correlation was found between specific strain types and BSI. However, among cases where B. cereus was isolated from blood specimens, there were cases with a high possibility of contamination at the time of sampling, as well as cases clearly manifesting as severe BSI leading to fatal acute B. cereus infections. It became evident that distinguishing between these clinical conditions is necessary.

Free Research Field

感染症疫学

Academic Significance and Societal Importance of the Research Achievements

本研究で収集した菌株の系統解析から、明確な相関は見いだせなかったものの、血流感染とST1420やST365 complexなどB. anthracisと近縁とされるclade1のCereusIIIとの関与を示唆する成果が得られた。また、我が国でB. cereus血流感染症が注目されやすい要因として、独自のST型が存在する可能性も示唆できた。B. cereusによる血流感染症のなかに、軽症型と劇症型の異なる病態があることを自験例と文献から明らかにし、血流感染と特定の系統株との明確な相関が示せなかった要因の一つとして、これらを区別せずに解析した点が考えられ、病態を明確にした解析の重要性を示した。