The Pathogenesis Of Lipopolysaccharide (LPS) From Cronobacter Sakazakii And The Intervention Of Bacteroides Fragilis

Cronobacter sakazakii is an opportunistic pathogenic that is easy to cause sepsis,meningitis and enterocolitis in the newborn,premature and low immunity people,the fatality rate is as high as 80%.There are fewer reports on the pathogenic effect about LPS from C.sakazakii and the intervention of Bacteroides fragilis.Extracting LPS from C.sakazakii by intraperitoneal injection in SD rat,DNA was extracted from the feces and the changes of the intestinal microflora were detected by sequencing.Paraffin sections were taken from the small intestine and colon to observe the degree of tissue damage.Serum samples were taken for detection of the expression of inflammatory cytokines TNF-?,IL-1?,IL-6,anti-inflammatory cytokines IL-10 and NO by ELISA kit;Intestinal RNA was extracted from the small intestine for fluorescent quantitative detection of intestinal tight junction protein,TLR4 and i NOS expression.The results showed that C.sakazakii LPS can cause disorders of the intestinal flora and affect the expression of inflammatory factors.On the whole,the inflammatory factors increased first and then gradually decreased.In addition,the expression of Claudin-4,Occludin,TLR4,and i NOS was also affected,and the intestinal tissues were damaged to varying degrees.Probiotics have a significant role in the treatment of intestinal diseases,and there are few reports on the probiotic effects of Bacteroides fragilis.So we carry on the intervention of Bacteroides fragilis NCTC 9343 on C.sakazakii LPS at this base.Administrate Bacteroidetes fragiles to SD rats five days before and after intraperitoneal injection C.sakazakii LPS.Then the colonic faeces,small intestine,colon,and serum were taken and investigated from the group of bacteria,tissue sections,inflammatory factors,genes,and protein levels.Results showed that the Bacteroides fragilis prevention group and the treatment group could improve the intestinal flora structure,and make the rats flora structure which infected C.sakazakii recovery to the direction of normal rats;At the same time,both experimental groups were able to reduce the level of inflammatory factors and have a significant regulatory effect on the expression of tight junction proteins,TLR4 and i NOS.This paper provides important basic data for the molecular mechanism of the pathogenicity of C.sakazakii LPS,and it is of great significance to effectively prevent and control the infection of the bacteria.