Neutralizing antibodies to Shiga toxin type 2 (Stx2) reduce colonization of mice by Stx2-expressing Escherichia coli O157:H7

Previously, we showed that the Shiga toxin type 2 (Stx2)-expressing Escherichia coli O157:H7 strain 86-24 colonized mice better than did its isogenic stx₂ negative mutant. Here, we confirmed that finding by demonstrating that Stx2 given orally to mice increased the levels of the 86-24 stx₂ mutant shed in feces. Then we assessed the impact of Stx2-neutralizing antibodies, administered passively or generated by immunization with an Stx2 toxoid, on E. coli O157:H7 colonization of mice. We found that such antibodies reduced the E. coli O157:H7 burden in infected mice and, as anticipated, also protected them from weight loss and death.     

应用高分辨率熔解曲线技术检测大肠埃希菌O157:H7志贺毒素基因变种stx2c

目的:探索高分辨率熔解曲线(High Resolution Melting,HRM)分析技术在检测大肠埃希菌O157:H7志贺毒素基因变种stx2c中的应用。方法:用HRM技术对20株O157:H7代表性菌株志贺毒素2基因进行分型,并与测序结果进行比较。结果:20份O157:H7样品中有3种类型熔解曲线。测序结果显示,12例A型熔解曲线中除1例为stx2a+stx2c杂合型外,其它均为原毒素基因型stx2a;1例B型熔解曲线测序结果为stx2a+stx2c杂合型,7例C型熔解曲线菌株测序结果均为stx2c纯合子。结论:HRM技术简便、快速,可作为志贺毒素2基因变种stx2c的检测方法。     

云南战区部队首次检出O157:H7大肠杆菌

[目的]了解EHEC O157：H7在云南战区部队腹泻患者和战区猪、牛和污水中的存在情况。[方法]在SMAC琼脂平板上分离，快速MUG试验初筛，用VITEK32自动微生物生化分析仪鉴定，复合PCR扩增法检测毒素基因。[结果]从人、猪、牛中分别检出EHEC O157：H7和EHECO157：H^-，其中O157：H7检出三个毒力基因。[结论]云南战区至少存在两种不同类型的EHEC O157，要警惕和预防此菌的感染。