Introduction. Bacillus cereus harbouring Ba813, a specific chromosomal marker of Bacillus anthtacis, is found in patients with severe manifestations and causes nosocomial outbreaks. Aim. We assessed the genetic characteristics and virulence of Ba813(+) B. cereus in a hospital setting. Methodology. Three neutropenic patients with haematological malignancy developed B. cereus bacteraemia within a short period. Fifteen B. cereus were isolated from different sites in a haematology ward. A total of 18 isolates were evaluated for Ba813- and B. anthracis -related virulence, food poisoning-related virulence, genetic diversity, bacteria motility and biofilm formation. Results. Ba813(+) B. cereus was detected in 33 % (1/3) of patients and 66 % (9/15) of the hospital environment. The 18 strains were divided into 2 major clusters (clade 1 and clade 2), and 14 strains were classified into clade 1. All Ba813(+) strains, including four sequence types, were classified into clade 1/the cereus III lineage, which is most closely related to the anthracis lineage. Two strains belonging to clade 1/non-cereus III carried the B. anthracis -associated cap gene, but not Ba813. B. cereus, including Ba813(+) strains, had significantly lower prevalence of enterotoxin genes than clade 2 strains. In clade 1, B. cereus , Ba813(+) strains showed significantly higher swimming motility and biofilm formation ability than Ba813(−) strains. Conclusion. Ba813(+) B. cereus , which are genetically closely related to B. anthracis , were abundant in a haematological ward. Ba813(+) B. cereus with high motility and biofilm formation abilities may spread easily in hospital environments, and could become a hospital-acquired infection.

中文翻译：

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在日本医疗中心对患有血液系统恶性肿瘤和医院环境的患者携带蜡状芽孢杆菌的Ba813进行鉴定。

介绍。 蜡样芽胞杆菌窝藏Ba813的特定染色体标记anthtacis芽孢杆菌，在重症患者表现发现并引起院内爆发。目标。我们在医院中评估了Ba813（+）蜡状芽孢杆菌的遗传特征和毒力。方法。三名血液系统恶性肿瘤的中性粒细胞减少患者在短时间内发展了蜡状芽孢杆菌菌血症。从血液病房的不同部位分离出十五种蜡状芽孢杆菌。总共对18株菌株进行了Ba813-和炭疽芽孢杆菌的评估 相关毒力，食物中毒相关毒力，遗传多样性，细菌运动性和生物膜形成。结果。 在33％（1/3）的患者和66％（9/15）的医院环境中检出了Ba813（+）蜡状芽孢杆菌。将18株菌株分为2个主要簇（第1株和第2株），将14株分为第1株。所有Ba813（+）菌株，包括4种序列类型，均分为第1株/蜡样III谱系。与炭疽血统最密切相关。属于进化枝1 /非蜡膜III的两个菌株携带了炭疽芽孢杆菌相关的cap基因，但没有携带Ba813。蜡状芽孢杆菌，包括Ba813 （+）菌株的肠毒素基因患病率明显低于进化枝2菌株。在进化枝1，蜡状芽孢杆菌，Ba813（+）菌株显示显著更高游泳运动性和生物膜形成的能力比Ba813（ - ）株。结论。Ba813（+）蜡状芽孢杆菌在遗传学上与炭疽芽孢杆菌密切相关，在血液病房中非常丰富。具有较高运动性和生物膜形成能力的蜡状芽孢杆菌Ba813（+）可能在医院环境中容易传播，并可能成为医院获得的感染。