Effect Of Prophylactic Application Of Saccharomyces Boulardii CNCM I-745 On Intestinal Flora In Rats Exposed To Antibiotics In The Early Life

Objective:To investigate the effect of prophylactic application of Saccharomyces boulardii CNCM I-745 on intestinal flora in rats exposed to antibiotics in the early life.Method:A total of 36 newborn SD rats were randomly divided into 3 groups(n=12,respectively):the antibiotic exposure group(Group A),the probiotic intervention group(Group B)and the normal saline control group(Group C).From the postnatal day 2(PND2)to PND6:The rats in the group A were given ceftriaxone by gavage(0.5mg/g,once a day,the gavage volume was 0.3ml),2 hours after which the rats were given normal saline by gavage(0.3ml,once a day).The rats in the group B were given ceftriaxone by gavage(0.5mg/g,once a day,the gavage volume is 0.3ml),2 hours after which the rats were given Saccharomyces boulardii CNCM I-745 by gavage(5×10~6CFU/g,once a day,the gavage volume is 0.3ml).The rats in group C were given normal saline by gavage twice a day(the gavage volume is 0.3ml).At PND7 and PND42,the rats were killed in each group(n=6,respectively).Their jejunal and colonic mucosa and the intestinal content were collected for next-generation sequencing(the V4 region of 16S r DNA).At PND42,jejunal and colonic tissues were collected from rats for observing the pathological change in intestinal tract.Result:At PND7,the body weight of rats in the group A and B was significantly higher than that in the group C,and the body of rats in the group A was lower than that in the group B.At PND21,the body weight of rats in the group A was significantly higher than that in the group B and C.At PND42,the body weight of rats in the group A and B was significantly higher than that in the group C,and the body weight of rats in the group A was higher than that in the group B(All P<0.05).No significant inflammatory changes or other pathological changes were observed in the jejunum and colon of rats among the 3 groups.At PND7,there was no statistically significant difference in Alpha diversity index and Beta diversity of jejunum flora among the 3 groups(P>0.05).At the level of phylum and genus,there was no statistically significant difference in jejunal flora distribution(P>0.05).At PND42,compared with group A,shannon,Observed＿species and PD＿whole＿tree index of jejunum flora in group B and group C decreased,and there were significant differences in Beta diversity between group A,group B and group C(P<0.05).Compared with group A,jejunum flora in phylum level increased significantly in group B,mainly Firmicutes,while the proportions of Bacteroidetes,Tenericutes,Proteobacteria and Cyanobacteria decreased significantly in group B.In genus level,the proportions of Lactobacillus in group B increased significantly.However,Klebsiella,Acinetobacter and Pseudomonas decreased(P<0.05).Only the difference of Shannon diversity index in Alpha diversity of jejunum flora in group B and group C was statistically significant.The proportion of Proteobacteria and Cyanobacteria in group C at portal level increased,while that of Euryarchaeota decreased,showing a statistically significant difference(P<0.05).At PND7,compared with group A and group B,only the difference in Shannon diversity index was statistically significant,while there was no difference in Beta diversity.At the portal level,the number of Proteobacteria,Bacteroidetes,Actinobacteria,Leptococcus,Deinococcus Thermus and Cyanobacteria in group B were mainly decreased,and the proportion of Firmicides was significantly increased.In genera level the concentrations of Lactococcus,Blastomonas,Chryseobacterium,Aquabacterium and Pseudomonas in group B decreased,with statistically significant differences(P<0.05).There were significant differences in Beta diversity between group B and group C,while there were no significant differences in Alpha diversity index and bacterial flora distribution.At PND42,compared with group A,shannon,Observed＿species and PD＿whole＿tree index in group B and group C were reduced,and there were significant differences in Beta diversity.The levels of colonic flora were increased mainly in Bacteroides,Chlorophyta,Saccharibacteria,and Firmicorites,while the proportion of Anoxybacillus was decreased mainly in genus,and the differences were statistically significant(P<0.05).Compared with group B,only Shannon diversity index was reduced in group C,and the difference in Beta diversity was not statistically significant.In the phylum level,Verrucomicrobia decreased in the group C,while Prevotellaceae＿UCG-001 and Turicibacter decreased in the group C,with statistically significant differences(P<0.05).Conclusion:The prophylactic application of Saccharomyces boulardii CNCM I-745during antibiotic exposure in early life can correct the changes of intestinal flora during puberty caused by antibiotic exposure in early life,but it cannot completely recover to the normal level.