Study On The Correlation Between Missed Abortion And Vaginal Microbiome

Objective:1.To demonstract the correlation between missed abortion and reproductive tract pathogen infection by Meta analysis.2.Studying the vaginal bacterial and fungal community structure of patients with missed abortion by high-throughput sequencing technology,compare the differences between them and normal early pregnancy women's vaginal flora structure,find specific bacteria,and reveal the correlation between missed abortion and changes in vaginal flora structure.Methods:1.Retrieve and collate the literature data on missed abortion published of CNKI,Wan Fang,Bai Du,Quan Fang,PubMed,Web of Science and other databases up to December 2019,collect the case-control research studies on reproductive tract pathogens of patients with missed abortion,screen out the eligible studies according to inclusion and exclusion criteria,and conduct quality evaluation.Literature data finally included in the study were extracted and statistically analyzed by StataSE12.0 software to systematically evaluate the relationship between lower genital tract infections and missed abortion.2.Eleven patients were selected from the obstetrics department of the Second Hospital of Lanzhou University from May 2018 to May 2019,including 10 cases in missed abortion group and 10 cases in normal early pregnancy group.Vaginal secretion samples were labeled A1,A2,A3...A10 and C1,C2...C10,respectively.16 S rDNA and ITS rDNA amplicon sequencing were performed.Sequencing data were analyzed by OTU cluster analysis and species annotation,Alpha diversity and Beta diversity analysis,and inter-group community difference analysis.The composition of microbial communities in the two groups was explored and the differences in vaginal flora structure between the two groups were compared.Results:1.Through Meta-analysis,it was found that the incidence of chlamydia trachomatis(CT),ureaplasma urealyticum(UU)infection in lower genital tract of patients with missed abortion was significantly higher than that of patients with normal early pregnancy(OR > 1,p < 0.05).2.In group A(missed abortion group),10 samples of vaginal bacterial biological communities produced 1406551 effective sequences,which were clustered into 21 OTUs under 97% similarity.A total of 3 phylum,6 classes,7 orders,8 families and 13 genera of bacteria were identified,among which dominant phylum,class,order,family and genera were Firmicutes(99%),Bacilli(98%),Lactobacillus(98%),Lactobacillus(98%),Lactobacillus(98%),Lactobacillus(98%)and Lactobacillus(98%).3.The main composition of group C(normal early pregnancy group)bacterial community except Lactobacillus,Gardnerella and Megacoccus were also higher in some samples.The relative abundance of Gardnerella fractions in samples C3,C4,C9 and C10 are all greater than 1%,and the relative abundance of Megasphaera in samples C4 and C9 are all greater than 1%.4.The distribution of Mycoplasma was detected in the vaginal secretions C5 of normal early pregnancy women,and its relative abundance was less than 0.004%.5.A total of 1682830 effective sequences were generated in the vaginal fungal community of 10 samples from group A,and 123 OTUs were clustered under 97% similarity.A total of 5 phylum,16 classes,30 orders,49 families and 55 genera of fungi were detected.Basidiomycota and Ascomycota are the most important phylum with relative abundance of more than 90%.The top 5 genera in relative abundance were Malassezia,Unclassified,Nakaseomyces,Rhodotorula and Aspergillus respectively.6.Alpha diversity analysis showed that there were significant differences in abundance of fungal microorganisms between group A and group C.According to the analysis of community abundance difference between the two groups,Kazachstania,Rhizopus and Rhodotorula are the species with the most significant difference in abundance between the two groups(p < 0.05).Conclusion:1.Vaginal microbial flora imbalance is closely related to missed abortion.Current studies have confirmed that chlamydia trachomatis and ureaplasma urealyticum are the colonies related to missed abortion.2.Compared with the vaginal microbiome of normal early pregnant women,no characteristic bacteria were found in the vaginal bacterial and fungal colonies of patients with embryo abortion.3.Significant changes in vaginal fungal flora abundance may be related to missed abortion,especially the significant increase in Rhizopus abundance should be noticed.