| Objective:To investigate the the short-and long-term effects of antibiotic exposure on the intestinal flora of rats in the early life.Methods:24 newborn rats were randomly divided into experimental group and control group?n=12?.On postnatal day 2?PND2?,the rats were given ceftriaxone by gavage for 5 days(0.5mg·g-1·d-1,once a day,the volume was 0.3ml),while rats in control group were given equivalent volume of normal saline,the weight,mental and activity status were observed in the two groups everyday.On PND7 and PND42 of the experiment,6 rats were sacrificed randomly in each group,the jejunal and colonic mucosas and the intestinal contents were collected to analyze the changes in intestinal flora using the 16S rDNA technique.On PND 42,the jejunal and colonic tissues were collected to observe the intestinal pathological changes and the length of intestinal villi and crypt depth were measured by using Image Pro Plus 6.0.Results:After exposure to ceftriaxone for 5 days,there was no significant difference in the diversity of jejunal flora?P>0.05?.The abundance of jejunal flora at phylum and genus levels also presented no statistically significant differences?P>0.05?.The diversity of colonic flora in experimental group was significantly higher than that in control group?P<0.05?.At the phylum level,the Bacteriodetes and Proteobacteria in experimental group were remarkably enriched,while Firmicutes was evidently down-regulated?P<0.05?,and difference in Actinobacteria showed no obvious change.At the genus level,the Acinetobacter,Staphylococcus,Enterococcus,Bacillus,Methanobrevibacter and Aerococcu of colonic floras in experimental group were notably increased compared with control group?P<0.05?.After termination of exposure to ceftriaxone for 5 weeks,The diversity of jejunum flora in the experimental group was significantly higher than that in the control group?P<0.05?.At the phylum level,there was no significant difference in the abundance of jejunum between the two groups.At the genus level,the Acinetobacter,Enterococcus,Lactococcus,and Yersinia in experimental group were largely increased compared with those in control group?P<0.05?.There was no statistical difference in the diversity of colonic flora between the two groups?P>0.05?,compared with the control group,the Firmicutes in the colonic flora in experimental group was increased obviously,while the Bacteroides were obviously decreased?P<0.05?.Proteobacteria and Actinomycetes had no statistically significant difference.At the genus level,it could be observed that,the Enterococcus,Staphylococcus,and Carnobacterium of Firmicutes were evidently increased,whereas the Prevotella and Parabacteroides of Bacteriodetes were notably decreased?P<0.05?.At PND7,PND21 and PND42,The weight in experimental group was markedly lower than that in control group?P<0.05?.No significant inflammatory changes and other pathological changes were detected in the jejunum and colon of rats,and there were no significant differences in the jejunal and colonic mucosal villi or crypt depth between experimental group and control group at PND42?P>0.05?.Conclusion:The Proteobacteria was mainly increased and Firmicutes was decreased on the intestinal flora of rats in the short-term after antibiotic exposured,and the relative abundance of potential pathogens were increased significantly.After termination of the antibiotic exposure until puberty,the intestinal flora of rats had not returned to normal,and it could be seen that the Firmicutes was increased and the Bacteroides was decreased significantly. |
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