Intestinal Microecology Research Articles

<i>Clostridium butyricum</i> Repairs the Intestinal Microecological Imbalance Caused by Antibiotics Based on the Integration of 16s rRNA Sequencing and Nontargeted Metabolomics Analysis

<i>Clostridium butyricum</i> Repairs the Intestinal Microecological Imbalance Caused by Antibiotics Based on the Integration of 16s rRNA Sequencing and Nontargeted Metabolomics Analysis

Polysaccharides from edible brown seaweed Undaria pinnatifida are effective against high-fat diet-induced obesity in mice through the modulation of intestinal microecology.

Brown seaweed is rich in polysaccharides including sulfated polysaccharides and alginate, both of which provide health benefits to the host but whose differences have not received sufficient attention. In this study, alginate from Undaria pinnatifida (UPA) and sulfated polysaccharides from U. pinnatifida (UPSP) were isolated, and their action was analyzed in high fat diet-fed mice. UPA and UPSP improved body composition, fat deposition in body tissues and organs, lipid abnormality and inflammatory response in mice, and compound polysaccharides from U. pinnatifida (UPP: UPA + UPSP) had a better effect on some physiological indexes, which could be attributed to the differences in the gut microbiota. Both UPSP and UPA modulated diet-induced microbiota dysbiosis, and UPP had better effect on changes in the gut microbiota, including an increase in Bacteroidales and reduction in both Clostridiales and Lactobacillales that had positive correlations with the improvement of the physiological status. The in vitro model of bacterial culture revealed that the use of Bacteroides on UPA and UPSP was species dependent, and UPP can better maintain the diversity and stability of the Bacteroidales community. This study indicated that polysaccharides from edible brown seaweed can benefit host health by improving the intestinal microecology, which can be helpful for the application of edible brown seaweed in health foods.

Effect of Xiaoning liquid on gut microbiota in asthmatic mice by 16S rDNA high-throughput sequencing

To investigate the effects of Xiaoning liquid on gut microbiota in mouse during asthma. A total of 60 mice were randomly and averagely assigned to healthy control group, control group, budesonide group, and Xiaoning liquid group. The later three groups were used to establish an Ovalbumin (OVA) asthma model. The intestinal bacterial communities were compared among groups using 16S rRNA gene amplification. Analyzing the structure of gut microbiota with OTU analysis, Shannon-Wiener, PCA, PCOA, etc. 16S rDNA high- throughput sequencing. The abundance and diversity of the gut microbiota in asthmatic mice increased, most obviously in the control group. The Bacteroidetes and Firmicutes levels increased in all asthmatic mice. The level of Bacteroides increased most obviously, making Bacteroides a useful marker of gut microbiota changes in asthmatic mice. The levels of Proteobacterium, Deferribacteraceae and Mucispirillum dropped significantly in the Xiaoning liquid group. Xiaoning liquid can reduce the species and numbers of pathogenic bacteria and restored the intestinal microecology of asthmatic mice. Xiaoning liquid has a positive effect on the function of gut microbiota.

The Effects of Delivery Mode on the Gut Microbiota and Health: State of Art.

The delivery mode is an important factor driving alteration in the gut microbiota during the neonatal period. Several studies prove that the alteration of gut microbiota induced by cesarean section could influence the activation of intestinal epithelial cells and the development of immune system. Further, some autoimmune and metabolic disorders may be related to the microbiota dysbiosis in infants caused by cesarean section. It is noteworthy that probiotics could promote the intestinal microecology, which may further prevent and treat cesarean section related diseases. This review summarized the great significance of delivery mode on microbiota and health, as well as provided clinically feasible methods for the prevention and treatment of cesarean section related gut diseases.

Treatment of Inflammatory Bowel Disease: A Comprehensive Review.

Inflammatory bowel disease (IBD), as a global disease, has attracted much research interest. Constant research has led to a better understanding of the disease condition and further promoted its management. We here reviewed the conventional and the novel drugs and therapies, as well as the potential ones, which have shown promise in preclinical studies and are likely to be effective future therapies. The conventional treatments aim at controlling symptoms through pharmacotherapy, including aminosalicylates, corticosteroids, immunomodulators, and biologics, with other general measures and/or surgical resection if necessary. However, a considerable fraction of patients do not respond to available treatments or lose response, which calls for new therapeutic strategies. Diverse therapeutic options are emerging, involving small molecules, apheresis therapy, improved intestinal microecology, cell therapy, and exosome therapy. In addition, patient education partly upgrades the efficacy of IBD treatment. Recent advances in the management of IBD have led to a paradigm shift in the treatment goals, from targeting symptom-free daily life to shooting for mucosal healing. In this review, the latest progress in IBD treatment is summarized to understand the advantages, pitfalls, and research prospects of different drugs and therapies and to provide a basis for the clinical decision and further research of IBD.

Dynamic changes of intestinal flora in patients with irritable bowel syndrome combined with anxiety and depression after oral administration of enterobacteria capsules

ABSTRACT This study investigated the clinical characteristics and dynamic changes of intestinal bacterial community to evaluate the curative effect of fecal microbiota transplantation (FMT) on irritable bowel syndrome with predominant diarrhea (IBS-D) comorbid with anxiety and depression. Total two treatments were designed in randomize-controlled trial includes oral FMT capsules with 1 week (A1), 8 weeks (A2), and 12 weeks (A3), as well as oral empty capsules with 1 week (B1), 8 weeks (B2), and 12 weeks (B3) as control for comparison. The positive therapeutic effects occurred in FMT colonized patient with IBS-D comorbid psychological disorder, demonstrated at alleviated IBS-D severity (IBS-SSS score from 291.11 reduced to 144.44), altered stool type (from 6 changed to 4), reduced anxiety and depression scores (from 18.33 to 8.39 and from 22.33 to 17.78) after FMT-treated 12 weeks. The FMT therapy improved bacterial alpha diversity and the majority bacterial community predominant by Bacteroidetes and Firmicutes, and the relative abundance (RA) was higher after FMT-treated 12 weeks (50.61% and 45.52%) than control (47.62% and 38.96%). In short, FMT therapy has great potential for IBS-D patients combined with anxiety and depression by alleviated clinical symptoms and restore the intestinal micro-ecology.

Characteristics of Intestinal Flora in Pregnant Women with Mild Thalassemia Revealed by Metagenomics

Background: At present, there is no report that the intestinal flora of pregnant women with mild thalassemia is different from that of healthy pregnant women. Objectives: This study compared the composition and changes of the intestinal flora of pregnant women with mild thalassemia to those of healthy pregnant women using metagenomic sequencing technology and evaluated the potential microecological risk for pregnant women and the fetus. Methods: The present study was carried out on 14 mild thalassemia pregnant women with similar backgrounds in the Affiliated Hospital of Putian University, Fujian, China. In the same period, 6 healthy pregnant women were selected as the control group. The genomic deoxyribonucleic acid was extracted from the sable stool samples of pregnant women. Illumina HiSeq sequencing technology was adopted after library preparation. Prodigal software (ver 2.6.3), Salmon software (ver 1.6.0), and Kraken software (ver 2) were used to analyze the sequence data. Moreover, analysis of variance and Duncan’s multiple-comparison test or Wilcoxon rank-sum test were used as statistical methods. Results: The characteristics of the intestinal flora of pregnant women with mild thalassemia differed significantly from those of healthy pregnant women, showing an increase in some conditionally pathogenic bacteria (e.g., Prevotella stercorea rose and Escherichia coli) and a decrease in some probiotic bacteria, which might affect pregnant women and cause physiological function damage to their offspring by changing metabolic pathways; however, further validation is needed. Conclusions: The diversity and composition of intestinal flora in pregnant women with mild thalassemia vary significantly from those in healthy pregnant women, especially at the genus and species levels, representing more profound alterations in intestinal microecology.

Lactobacillus plantarum MA2 Ameliorates Methionine and Choline-Deficient Diet Induced Non-Alcoholic Fatty Liver Disease in Rats by Improving the Intestinal Microecology and Mucosal Barrier.

Non-alcoholic fatty liver disease (NAFLD) has become a highly concerned health issue in modern society. Due to the attentions of probiotics in the prevention of NAFLD, it is necessary to further clarify their roles. In this study, the methionine and choline-deficient (MCD) diet induced NAFLD rats model were constructed and treated with strain L. plantarum MA2 by intragastric administration once a day at a dose of 1 × 108 cfu/g.bw. After 56 days of the therapeutic intervention, the lipid metabolism and the liver pathological damage of the NAFLD rats were significantly improved. The content of total cholesterol (TC) and total triglyceride (TG) in serum were significantly lower than that in the NAFLD group (p < 0.05). Meanwhile, the intestinal mucosal barrier and the structure of intestinal microbiota were also improved. The villi length and the expression of claudin-1 was significantly higher than that in the NAFLD group (p < 0.05). Then, by detecting the content of LPS in the serum and the LPS-TLR4 pathway in the liver, we can conclude that Lactobacillus plantarum MA2 could reduce the LPS by regulating the gut microecology, thereby inhibit the activation of LPS-TLR4 and it downstream inflammatory signaling pathways. Therefore, our studies on rats showed that L. plantarum MA2 has the potential application in the alleviation of NAFLD. Moreover, based on the application of the strain in food industry, this study is of great significance to the development of new therapeutic strategy for NAFLD.

Effects of Dietary Mannan Oligosaccharides on Non-Specific Immunity, Intestinal Health, and Antibiotic Resistance Genes in Pacific White Shrimp Litopenaeus vannamei.

This study was conducted to comprehensively investigate the beneficial effects of a mannan oligosaccharide product (hereinafter called MOS) on Litopenaeus vannamei and optimum level of MOS. Five isonitrogenous and isolipid diets were formulated by adding 0%, 0.02%, 0.04%, 0.08%, and 0.16% MOS in the basal diet. Each diet was randomly fed to one group with four replicates of shrimp in an 8-week feeding trial. The results showed that dietary MOS improved the growth performance and the ability of digestion of shrimp. Dietary MOS significantly increased the activity of total superoxide dismutase, catalase, and glutathione peroxidase and decreased the content of malondialdehyde in plasma of shrimp. Dietary MOS significantly increased the activity of alkaline phosphatase and lysozyme in plasma and the hemocyte counts. Dietary MOS significantly upregulated the expression of Toll, lysozyme, anti-lipopolysaccharide factor, Crustin, and heat shock protein 70 in the hepatopancreas. And dietary MOS significantly upregulated the expression of intestinal mucin-2, mucin-5B, and mucin-19, while it decreased the expression of intestinal mucin-1 and macrophage migration inhibitory factor. Dietary MOS improved the bacterial diversity; increased the abundance of Lactobacillus, Bifidobacterium, Blautia, and Pseudoalteromonas; and decreased the abundance of Vibrio in the intestine. Shrimp fed MOS diets showed lower mortality after being challenged by Vibrio parahaemolyticus. Notably, this study found a decrease in antibiotic resistance genes and mobile genetic elements after MOS supplementation for the first time. The present results showed that diet with MOS supplementation enhanced the organismal antioxidant capacity and immunity, improved intestinal immunity, optimized intestinal microecology, mitigated the degree of antibiotic resistance, and increased the resistance to V. parahaemolyticus in L. vannamei, especially when supplemented at 0.08% and 0.16%.

Effects of Xylooligosaccharides on Lipid Metabolism, Inflammation, and Gut Microbiota in C57BL/6J Mice Fed a High-Fat Diet.

Xylooligosaccharide (XOS) is a source of prebiotics with multiple biological activities. The present study aimed to investigate the effects of XOS on mice fed a high-fat diet. Mice were fed either a normal diet or a high-fat diet supplemented without or with XOS (250 and 500 mg/kg), respectively, for 12 weeks. The results showed that the XOS inhibited mouse weight gain, decreased the epididymal adipose index, and improved the blood lipid levels, including triglyceride (TG), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) levels. Moreover, XOS reduced the activity of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), and alleviated the damage to the liver caused by the high-fat diet. XOS also reduced hyperlipidemia-associated inflammatory responses. Additionally, quantitative real-time polymerase chain reaction results showed that XOS intervention activated the AMP-activated protein kinase (AMPK) pathway to regulate the fat synthesis, decomposition, and β oxidation; upregulated the mRNA expression levels of carnitine palmitoyl transferase 1 (CPT-1), peroxisome proliferator–activated receptors α (PPAR-α), and cholesterol 7-alpha hydroxylase (CYP7A1); and downregulated the mRNA expression levels of acetyl-CoA carboxylase (ACC), CCAAT/enhancer-binding protein alpha (C/EBPα), and lipoprotein lipase (LPL). On the other hand, XOS enhanced the mRNA expression levels of zonula occludens-1 (ZO-1), occludin, and claudin-1 in the small intestine; increased the strength of the intestinal barrier; and optimized the composition of the intestinal microbiota. Therefore, it was concluded that XOS regulated the intestinal barrier, changed the intestinal microecology, and played an important role in preventing hyperlipidemia through the unique anatomical advantages of the gut–liver axis.

Electroacupuncture modulates the intestinal microecology to improve intestinal motility in spinal cord injury rats.

SummarySpinal cord injury (SCI) is a disease involving gastrointestinal disorders. The underlying mechanisms of the potential protective effects of electroacupuncture (EA) and 5‐hydroxytryptamine (5‐HT) system on SCI remain unknown. We investigated whether EA improves gut microbial dysbiosis in SCI and regulates the 5‐HT system. 16S rDNA gene sequencing was applied to investigate alterations in the gut microbiome of the rats. Faecal metabolites and the expression of the 5‐HT system were detected. EA and faecal microbiota transplantation (FMT) treatment facilitated intestinal transmission functional recovery and restored the colon morphology of SCI rats. The composition of the intestinal microbiota, including numbers of phylum Proteobacteria, class Clostridia, order Bacteroidales, and genus Dorea, were amplified in SCI rats, and EA and FMT significantly reshaped the intestinal microbiota. SCI resulted in disturbed metabolic conditions in rats, and the EA and FMT group showed increased amounts of catechin compared with SCI rats. SCI inhibited 5‐HT system expression in the colon, which was significantly reversed by EA and FMT treatment. Therefore, EA may ameliorate SCI by modulating microbiota and metabolites and regulate the 5‐HT system. Our study provides new insights into the pathogenesis and therapy of SCI from the perspective of microbiota and 5‐HT regulation.

Reconstruction of intestinal microecology of type 2 diabetes by fecal microbiota transplantation: Why and how.

Type 2 diabetes (T2D) is a chronic metabolic disease characterized by hyperglycemia due to insulin resistance. Mounting evidence has correlated T2D to alterations in the composition of gut microbiota. Accordingly, targeting the gut microbiota has become an emerging strategy for T2D management. The aim of this article is to get a better insight into the rationale for targeting gut microbiota in T2D treatment. Thus, we herein reviewed the change of gut microbiota composition in T2D, factors shaping gut microbiota, and potential mechanisms behind the contribution of gut microbiota to T2D pathogenesis. At present, it has become possible to use intestinal microorganism capsules, bacteria liquid, and other preparations to carry out fecal microbiota transplantation for the treatment and intervention of T2D with insulin resistance and immune-mediated type 1 diabetes.

Research progress on intestinal microecology regulating mechanism and biological activities of polysaccharides

Intestinal microecology is an important defense system in the human body. The intestinal flora is the core micro-ecosystem in the human intestine. It has a symbiotic relationship with the overall functions of the body. It has strong metabolic activity to maintain the normal functioning of the body and resist the invasion of various viral antigens in the body. Playing a protective function,the imbalanced intestinal microecology can cause various diseases. Polysaccharides can be extracted from a wide range of sources and have low toxicity and side effects. They have attracted wide attention because of their anti-tumor, anti-oxidant, anti-inflammatory and other biological activities. Studies have demonstrated that polysaccharides can regulate intestinal microecological disorders. According to the studies in recent years, this review summarizes that polysaccharides mainly modulate intestinal microecological disorders through regulating the composition of intestinal flora, improving the metabolism of the flora, and repairing the intestinal tract barrier. On the basis of these mechanisms of action, this paper elaborates the anti-tumor, immunomodulatory, and anti-inflammatory activities of polysaccharides. This paper can provide reference for the future research on the intestinal microecology-regulating mechanism and biological activities of polysaccharides.

Research progress of the effect of enteral nutrition on intestinal microecology in neurocritical ill patients

The intestinal flora and the intestinal environment in which it resides together constitute the intestinal microecosystem,it is significantly disturbed in neurocritical ill patients, as manifested by the decrease of bacterial diversity, an increase of pathogen, and the destruction of the intestinal barrier. Appropriate enteral nutrition is effective in maintaining intestinal barrier stability, regulating intestinal immune function, inhibiting intestinal inflammation, and regulating specific intestinal microbiota and intestinal function. It is important for sustaining intestinal microecological balance, reducing clinical complications in patients, and is a new target for the treatment of neurocritical ill patients. This review elaborates the alteration of intestinal microecology and treatment options recommended by current clinical guidelines in neurocritical ill patients and summarizes the research progress of the effects of enteral nutrition and several nutritional additives on intestinal flora and intestinal functions, to provide a reference for the follow-up research.

The Main Mechanisms of the Effect of Intestinal Microflora on the Immune System and Their Importance in Clinical Practice

The intestinal microflora protects humans from colonization by pathogenic microorganisms and inhibits their growth. It is known that one of the functions of normal flora is to activate not only the local immunity of the intestine, but also the system of the whole organism. Today, probiotic preparations with immunomodulatory effects are widely used in medical practice, containing Lactobacillus Acidophilus NCFMTM, Bifidobacterium Lactis BL-04, which support local and general immunity. Research results indicate that probiotics are effective in the treatment of many pathological conditions in both children and adults due to their various positive effects on health, including due to their immunomodulatory effects. The use of probiotics in complex therapy allows you to quickly achieve a stable normalization of the composition of the intestinal microflora and eliminate pathological manifestations of the disease. The fundamental importance of probiotics is that they allow the treatment of disorders of intestinal microecology, caused by both the external environment and oral antimicrobial therapy. Several probiotics have been shown to shorten the duration and ease the course of bacterial or viral respiratory infections. The effect of probiotics on the immune system is multifaceted and promising for the correction of cytokine production, which is especially important in the context of the SARS-CoV2 pandemic.

Purslane (Portulacae oleracea L.) attenuates cadmium-induced hepatorenal and colonic damage in mice: Role of chelation, antioxidant and intestinal microecological regulation

BackgroundCadmium (Cd) is a representative pernicious metal, which has high biological toxicity. Its precaution through dietary administration is considered an important strategy. Considering that Portulaca oleracea L. (Por.L) has antioxidant, anti-inflammatory and other high medicinal value, and purslane insoluble dietary fiber (PIDF) has good binding property to metal ions, they could be good methods for Cd-induced biotoxicity therapy. PurposeTo investigate the beneficial effects of Por.L or PIDF against Cd-induced subchronic toxicity and identify its underlying mechanisms. Study design and MethodsC57BL/6 male mice (n = 12) were received 100 mg l−1 CdCl2 in water for 8 weeks. Mice were divided into four groups: Control, Cd-treated, 8% Por.L + Cd, and 8% PIDF + Cd. Histological evaluation, inductively coupled plasma-mass spectrometry, western blotting analysis, quantitative real time-PCR, gas chromatography-mass spectrometry and 16S rDNA analysis were used in the study. Results: Por.L treatment was able to inhibit inflammation and accumulation of Cd, enhance the activity of antioxidant enzymes, increase beneficial bacterial species of Akkermansia and Faecalibaculum and suppress the production of inflammatory cytokines in the colon, such as TNF-α, IL-6, IL-1β and IFN-γ. PIDF mainly relieved the toxicity of Cd by increasing the production of short chain fatty acids with anti-inflammatory functions and repressing the liver and kidney inflammation mediated by the TLR4/ MyD88/NF-κB pathway. Conclusion: Our study has demonstrated that the antagonistic-Cd effects of Por.L might be mediated via chelation, antioxidation, regulation of intestinal microecology. Thus, our study provides a novel insight into Por.L as a promising function food for the anti-Cd biotoxicity. Por.L supplement could be considered as a potential coping strategy to alleviate hazardous effects in Cd-exposed humans.

Discussion on the Theoretical Basis for Acupuncture to Improve Knee Osteoarthritis from "Intestinal Microecology"

The balance of the intestinal microecosystem is essentially consistent with the theory of "Yin Ping Yang Mi" in Chinese medicine. The imbalance of the intestinal microenvironment's homeostasis is closely related to the occurrence of diseases. Acupuncture and moxibustion can improve the disease state by regulating the stability of the intestinal microecology, which has a certain theoretical basis. By exploring the law of the body's meridian circulation, it provides a theoretical basis for studying the regulation of acupuncture on the intestinal microecology of patients with knee osteoarthritis (KOA).

Discussion on the Intestinal Microecological Status of Patients with Liver Cirrhosis and Liver Cirrhosis Complicated with Diabetes Mellitus

Discussion on the Intestinal Microecological Status of Patients with Liver Cirrhosis and Liver Cirrhosis Complicated with Diabetes Mellitus

MiR155 Disrupts the Intestinal Barrier by Inducing Intestinal Inflammation and Altering the Intestinal Microecology in Severe Acute Pancreatitis.

Intestinal dysfunction is a common complication of acute pancreatitis. MiR155 may be involved in the occurrence and development of intestinal dysfunction mediated by acute pancreatitis, but the specific mechanism is not clear. To investigate the effect of miR155 on severe acute pancreatitis (SAP)-associated intestinal dysfunction and its possible mechanism in a mice model. In this study, SAP mice model was induced by intraperitoneal injection of caerulein and LPS in combination. Adeno-associated virus (AAV) was given by tail vein injection before the SAP model. The pancreatic and intestinal histopathology changes were analyzed. Cecal tissue was collected for 16S rRNA Gene Sequencing. Intestinal barrier proteins ZO-1 and E-cad were measured by Immunohistochemistry Staining and Western Blot, respectively. Intestinal tissue miR155 and inflammatory factors TNF-α, IL-1β, and IL-6 were detected by Q-PCR. The expression levels of protein associated with TNF-α and TLR4/MYD88 pathway in the intestinal were detected. In miR155 overexpression SAP group, the levels of tissue inflammatory factor were significantly increased, intestinal barrier proteins were significantly decreased, and the injury of intestinal was aggravated. Bacterial 16S rRNA sequencing was performed, showing miR155 promotes gut microbiota dysbiosis. The levels of TNF-α, TLR4, and MYD88 in the intestinal were detected, suggesting that miR155 may regulate gut microbiota and activate the TLR4/MYD88 pathway, thereby affecting the release of inflammatory mediators and regulating SAP-related intestinal injury. After application of miR155-sponge, imbalance of intestinal flora and destruction of intestinal barrier-related proteins have been alleviated. The release of inflammatory mediators decreased, and the histopathology injury of intestinal was improved obviously. MiR155 may play an important role in SAP-associated intestinal dysfunction. MiR155 can significantly alter the intestinal microecology, aggravated intestinal inflammation through TLR4/MYD88 pathway, and disrupts the intestinal barrier in SAP mice.

Effect of intestinal microecology on postnatal weight gain in very preterm infants in intensive care units

ObjectiveTo study the effect of intestinal microecology on postnatal weight gain of very preterm infants in neonatal intensive care unit (NICU).MethodsVery preterm infants who met the inclusion criteria were enrolled. The subjects were divided into the extrauterine growth retardation (EUGR) group(defined as a body weight less than the 10th percentile of the corresponding gestational age or a weight loss between birth and a given time of > 2SD were considered EUGR) and normal growth group, and the growth was evaluated at 2 and 4 weeks after birth. Meanwhile, the stool samples were taken to perform16S ribosomal RNA (rRNA) high -throughput 16S rRNA sequencing of the intestinal microflora was performed on stool samples.ResultsA total of 22 infants were included. There was no significant difference in the alpha diversity indexes indices between the two groups at 2 weeks or 4 weeks after birth. The beta diversity analysis showed that the two groups had similar principal components of the intestinal microflora were similar between the two groups. Linear discriminant analysis (LDA) effect size (LEfSe) showed that 2 weeks after birth, the bacteria with an absolute LDA score (log10) higher than 4 included Streptococcaceae, Streptococcus, Bacteroidetes, Bacteroidales and Stenotrophomonas in the EUGR group and Enterococcaceae and Enterococcus in the control group. At the 4th week after birth, the bacteria with an absolute LDA score (log10) higher than 3 in the EUGR group includedwere Clostriaceae, Eubacteriaceae and Eubacterium. TheBy comparing the composition of the microbial community composition comparison showed, significant differences were found in the principal components of Enterococcus and Streptococcus on the family and genus levels at 2 weeks after birth. No Bifidobacterium was found in either group at 4 weeks after birth.ConclusionIntestinal microecology is different between infants with EUGR and those with normal growth. The diversity and richness of the intestinal microflora in preterm infants at the NICU are significantly insufficient and change dynamically with time, and the establishment of intestinal homeostasis is obviously delayed.