Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Schönleutnerstr. 8, 85764, Oberschleißheim, Germany.
Functional Microbiology, Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna, 1210, Vienna, Austria.
Food Microbiol. 2019 Dec;84:103276. doi: 10.1016/j.fm.2019.103276. Epub 2019 Jul 22.
The diarrheal type of food poisoning caused by enteropathogenic Bacillus cereus has been linked to various exotoxins. Best described are the non-hemolytic enterotoxin (Nhe), hemolysin BL (Hbl), and cytotoxin K (CytK). Due to the ubiquitous prevalence of B. cereus in soil and crops and its ability to form highly resistant endospores, contaminations during food production and processing cannot be completely avoided. Although phylogenetically closely related, enteropathogenic B. cereus strains show a high versatility of their toxic potential. Thus, functional tools for evaluating the pathogenic potential are urgently needed in order to predict hazardous food contaminations. As the diarrheal syndrome is the result of a toxico-infection with enterotoxin production in the intestine, the entire passage of the bacteria within the host, from spore survival in the stomach, spore germination, host cell adherence, and motility, to enterotoxin production under simulated intestinal conditions was compared in a panel of 20 strains, including high pathogenic as well as apathogenic ones. This approach resulted in an overarching virulence analysis scheme. In parallel, we searched for potential toxico-specific secreted markers to discriminate low and high pathogenic strains. To this end, we targeted known exotoxins using an easy to implement immunoblotting approach as well as a caseinolytic exoprotease activity assay. Overall, Nhe component B, sphingomyelinase, and exoproteases showed good correlation with the complex virulence analysis scheme and can serve as a template for future fast and easy risk assessment tools to be implemented in routine diagnostic procedures and HACCP studies.
由产肠毒素蜡样芽胞杆菌引起的腹泻型食物中毒与各种外毒素有关。其中描述最好的是非溶血肠毒素（Nhe）、溶血素 BL（Hbl）和细胞毒素 K（CytK）。由于蜡样芽胞杆菌在土壤和农作物中普遍存在，并且能够形成高度抗逆的芽孢，因此在食品生产和加工过程中无法完全避免污染。尽管产肠毒素蜡样芽胞杆菌菌株在系统发育上密切相关，但它们的毒性潜力具有很高的多功能性。因此，迫切需要功能工具来评估其致病潜力，以便预测危险的食物污染。由于腹泻综合征是由于肠内产生肠毒素的毒感染引起的，因此在一组 20 株菌中比较了细菌在宿主内的整个传递过程，包括高致病性和非致病性菌株，从孢子在胃中的存活、孢子萌发、宿主细胞黏附、运动到模拟肠道条件下的肠毒素产生。这种方法导致了一个全面的毒力分析方案。同时，我们还寻找了潜在的毒力特异性分泌标志物，以区分低致病性和高致病性菌株。为此，我们使用一种易于实施的免疫印迹方法和一种酪蛋白水解外肽酶活性测定法，针对已知的外毒素。总的来说，Nhe 成分 B、神经鞘磷脂酶和外肽酶与复杂的毒力分析方案有很好的相关性，可以作为未来快速、简便的风险评估工具的模板，用于常规诊断程序和 HACCP 研究。
