Department of Obstetrics and Gynecology, Peking University First Hospital, Beijing, China; Beijing Key Laboratory of Maternal Fetal Medicine of Gestational Diabetes Mellitus, Beijing, China.
COYOTE Medical Laboratory, Beijing, China.
Am J Obstet Gynecol. 2020 Aug;223(2):248.e1-248.e21. doi: 10.1016/j.ajog.2020.01.056. Epub 2020 Feb 1.
There is controversy about whether the amniotic fluid contains bacteria. With the use of sequencing-based methods, recent studies report that the amniotic fluid is colonized by microorganisms. However, background-contaminating DNA might lead to false-positive findings when such a low microbial biomass sample is examined.
The purpose of this study was to determine whether the midtrimester amniotic fluid of patients who subsequently had normal pregnancy outcomes contains a microbial signature.
In this prospective cohort study, 42 amniotic fluid samples were collected from 37 pregnancies (5 twin and 32 singletons) during genetic amniocentesis in the midtrimester. The subsequent pregnancy outcomes of all the participants were followed. Multiple methods were used to detect the presence of microorganisms in this study, which included cultivation, quantitative real-time polymerase chain reaction, and 16S ribosomal RNA gene sequencing. Multiple positive control samples (n=16) served as quality control samples and included 3 adult fecal samples, 4 vaginal swabs, and 9 artificial bacterial communities that were run in parallel with negative control samples (n=12) that included 4 samples from the hospital operating room and 8 samples from the laboratory, to account for background-contaminating DNA during each step of the experiments.
No bacteria under anaerobic or aerobic conditions or genital mycoplasmas were cultured from any of the amniotic fluid samples. Quantitative polymerase chain reaction did not reveal greater copy numbers of 16S ribosomal RNA gene in amniotic fluid samples than in negative control samples. 16S Ribosomal RNA gene sequencing did not indicate a significant difference in the microbial richness or community structures between amniotic fluid and negative control samples.
With multiple methods of microbiologic inquiry, no microorganisms were identified in the midtrimester amniotic fluid of healthy pregnancies with a normal pregnancy outcome.
关于羊水是否含有细菌存在争议。最近的研究使用基于测序的方法报告称，羊水被微生物定植。然而，当检查这种微生物生物量低的样本时，背景污染的 DNA 可能导致假阳性结果。
本研究旨在确定随后妊娠结局正常的患者的中期羊水是否存在微生物特征。
在这项前瞻性队列研究中，在中期遗传羊膜穿刺术期间从 37 例妊娠（5 例双胎和 32 例单胎）中收集了 42 份羊水样本。所有参与者的后续妊娠结局均得到随访。本研究采用多种方法检测微生物的存在，包括培养、定量实时聚合酶链反应和 16S 核糖体 RNA 基因测序。多个阳性对照样本（n=16）作为质量控制样本，包括 3 份成人粪便样本、4 份阴道拭子和 9 份人工细菌群落，与阴性对照样本（n=12）平行运行，阴性对照样本包括 4 份来自医院手术室和 8 份来自实验室的样本，以解释实验过程中每个步骤的背景污染 DNA。
没有从任何羊水样本中培养出厌氧或需氧条件下的细菌或生殖支原体。定量聚合酶链反应未显示羊水样本中 16S 核糖体 RNA 基因的拷贝数高于阴性对照样本。16S 核糖体 RNA 基因测序未表明羊水和阴性对照样本之间的微生物丰富度或群落结构存在显著差异。
使用多种微生物学探究方法，在妊娠结局正常的健康妊娠中期羊水中未鉴定出微生物。
