| Objective:Spontaneous bacterial translocation from gastro- intestinal is a common phenomenon among healthy neonates. The aim of this study is to observe this spontaneous bacterial translocation and bacterial colonization of the gut to systematically study the relationship between them and we also arranged a group of rats receiving antibiotics so that we can study the influence of antibiotics on the Spontaneous bacterial translocation and the intestinal bacterial colonization.We also analysis the interaction of translocation of bacterial in MLN and CD25/CD3, and their influence by antibiotics, explain bacterial antigen and antibiotics influence on neonatal rat immune system set up, therefore provide evidence for clinic protection, improve neonates normal immune system set up and decrease the rate of infection and mortality.The aim of the study is to increase the clinical worker's awareness of protecting the intestinal microecosystem to avoid and reduce the side effects of dysbacteriosis on organism.Methods:Timed-gestation pregnant SD rats were pur- chased from Hebei Medical University.Animals had free access to water and regular chow. Rats were allowed to deliver spontaneously.Pups suckled ad libitum with their dams and ate regular chow after weaning.A total of 100 rats were assigned to five different groups depending on age.And another 20 pups were given antibiotics abdominally right after delivery for 7 days.Animals were killed by cervical dislocation either immediately or at 3,7,14 and 30 days after deliverly.Using sterile procedures,the mesenteric lymph node (MLN) complex,spleen,liver and the terminal ileal loop were excised,weighted,homogenized and diluted. Portions of proper dilutions were plated on four different plates to culture for aerobic and facultative anaerobic gram-positive bacteria,aerobic and facultative anaerobic gram-negative bacilli,lactobacilli and bifidobacteria respectively.Bacteria were identified by using API system ,biochemistry reaction and spectrum analysis. Each rat's spleen was sampled and made into mononuclear cell's supernatant. Use flow cytometry to measure the quantities of CD3 and CD25 cells.Result1 Bacterial Colonization of the Gut. Cultures from the terminal ileal loop were sterile immediately after birth.Gram-positive cocci were the first to settle and were found in 60% of rats on day 3.Gram-negative bacteria were less abundant on day 3,but by day 7 gram-negative bacteria were found in almost all animals.lactobacilli and bifidobacteria had colonized about 40% of animals on day 3. Beyond day 7, they were found in all animals and became the numerically dominant population among intestinal microflora.2 The effect of antibiotics on bacteria colonization in infant rats:When given antibiotics,the number of gram-positive bacteria and gram-negative bacilli increased noticeably, and the number of lactobacilli and bifidobacteria decreased.The composition of intestinal bacteria changed.3 Translocation of Indigenous Bacteria: All bacterial cultures abtained from extraintestinal organs immediately after birth remained negative.Similarly,no bacteria were isolated from extraintestinal organs in rat pups with negative ileal cultures on day 3.as the gut was colonized by bacteria ,translocation to the MLN,liver,and spleen was noted in a varying number of rats.On day 3 bacteria had translocated to the MLN in 40% of animals and on day 14 the incidence of traslocation to the MLN had reached 80%.Thereafter ,translocation to the MLN fell gradually.However,30% of MLN remained positive on day 30. Translocation to the liver also started early, peaked on day 7 and then decreased quickly.On day 30,all cultures of liver were negative.4 The effect of antibiotics on bacteria translocation in infant rats:Compared to normal pups,those received antibiotics have higher incidence of bacteria translocation and the number of translocated bacterial was also higher than that of normal pups.5 The correlation of bacteria translocation and the immune system in infant rats: the quanti... |
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