嗜酸乳杆菌抑制大肠杆菌O157：H7肠道定植体内外实验

摘要

Objective To test the inhabiting effect of Lactobacillus acidophilus on E.coli O157: H7 in intestinal colonization and explore its mechanism. Methods The suppressive effects of Lactobacillus acidophilus against E.coli O157:H7 adhering to Ht29 cells were carried out by competition , exclusion and replacement as-says. Furthermore, we evaluated the cytokine levels of IL-4, IL-12, and INF-γ in serum of mice. In addition, E.coli O157:H7 fecal shedding was monitored and the pathological changes of intestines were observed in mice. Results The competition, exclusion and replacement assays showed Lactobacillus acidophilus inhibited E.coli O157:H7 adhering to Ht29 cells. In vivo, the mice of treatment group were induced significantly higher level of IL-4, IL-12, and INF-γ, though prevention group induced IL-12 only. Fifteen days after E.coli O157:H7 infec-tion, there were 8 mice (80%) in prevention group and 5 mice (50%) in treatment group stopped shedding. Moreover, the pathological changes of intestines of both prevention group and treatment group appeared normal , but control groups showed seriously damaged in intestinal villus. Conclusion Lactobacillus acidophilus inhibits E.coli O157:H7 in intestinal colonization and the preventative effect was better than treatment effect. Thus , Lac-tobacillus acidophilus can be used for E.coli O157:H7 in prevention and treatment infection as probiotics.%目的：考察嗜酸乳杆菌抑制大肠杆菌 O157：H7在肠道定植的效果并探讨其作用机制。方法：通过竞争、排斥和置换试验，体外检测嗜酸乳杆菌抑制大肠杆菌O157：H7黏附Ht29细胞的作用，并通过体内实验，检测小鼠血清中细胞因子IL-4、IL-12和 INF-γ的表达水平，监测攻毒后小鼠粪便排菌量和肠道病理切片观察。结果：体外竞争、排斥和置换实验表明嗜酸乳杆菌均可抑制大肠杆菌 O157：H7黏附 Ht29细胞；体内实验中治疗组均可诱导小鼠产生较高水平的 IL-4、IL-12和INF-γ，而预防组仅提高IL-12表达水平；攻毒后15 d 检测表明预防组有8只（80％）小鼠结束排菌，治疗组有5只（50％）小鼠结束排菌，且两组小鼠肠绒毛完整，基本无病理变化，而对照组小鼠肠道肠绒毛损伤严重。结论：嗜酸乳杆菌可抑制大肠杆菌O157：H7肠道定植，预防效果优于治疗效果，可作为防治大肠杆菌O157：H7感染的益生菌菌剂。