Inhibiting effect of Lactobacillus acidophilus on intestinal colonization of enterohaemorrhagic E.coli O157:H7 in vitro and vivo / 实用医学杂志

ABSTRACT

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 O157H7 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 O157H7 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 O157H7 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 O157H7 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 O157H7 in intestinal colonization and the preventative effect was better than treatment effect. Thus , Lac-tobacillus acidophilus can be used for E.coli O157H7 in prevention and treatment infection as probiotics.