BACKGROUND Only a few microbial studies have conducted in IVF (in vitro fertilization), showing the high-variety bacterial contamination of IVF culture media to cause damage to or even loss of cultured oocytes and embryos. We aimed to determine the prevalence and counts of bacteria in IVF samples, and to associate them with clinical outcome. METHODS The studied samples from 50 infertile couples included: raw (n = 48), processed (n = 49) and incubated (n = 50) sperm samples, and IVF culture media (n = 50). The full microbiome was analyzed by 454 pyrosequencing and quantitative analysis by real-time quantitative PCR. Descriptive statistics, t-, Mann-Whitney tests and Spearman's correlation were used for comparison of studied groups. RESULTS The study involved normozoospermic men. Normal vaginal microbiota was present in 72.0% of female partners, while intermediate microbiota and bacterial vaginosis were diagnosed in 12.0 and 16.0%, respectively. The decreasing bacterial loads were found in raw (35.5%), processed (12.0%) and sperm samples used for oocyte insemination (4.0%), and in 8.0% of IVF culture media. The most abundant genera of bacteria in native semen and IVF culture media were Lactobacillus, while in other samples Alphaproteobacteria prevailed. Staphylococcus sp. was found only in semen from patients with inflammation. Phylum Bacteroidetes was in negative correlation with sperm motility and Alphaproteobacteria with high-quality IVF embryos. CONCLUSION Our study demonstrates that IVF does not occur in a sterile environment. The prevalent bacteria include classes Bacilli in raw semen and IVF culture media, Clostridia in processed and Bacteroidia in sperm samples used for insemination. The presence of Staphylococcus sp. and Alphaproteobacteria associated with clinical outcomes, like sperm and embryo quality.

中文翻译：

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在人类体外受精过程中，从天然精液到胚胎培养环境的复杂微生物组。

背景技术在体外受精（体外受精）中仅进行了少数微生物研究，显示出体外受精（IVF）培养基受到多种细菌污染，导致培养的卵母细胞和胚胎受损甚至丢失。我们旨在确定IVF样品中细菌的流行率和数量，并将其与临床结果相关联。方法研究的来自50对不育夫妇的样品包括：未加工的（n = 48），加工的（n = 49）和温育的（n = 50）精子样品，以及IVF培养基（n = 50）。通过454焦磷酸测序分析完整的微生物组，并通过实时定量PCR进行定量分析。描述性统计学，t检验，Mann-Whitney检验和Spearman相关性用于比较研究组。结果该研究涉及正常精子症男性。正常的阴道菌群存在于72中。女性伴侣为0％，而中度微生物群和细菌性阴道病的诊断率分别为12.0％和16.0％。在用于卵母细胞受精的未加工样品（35.5％），加工样品（12.0％）和精子样品（4.0％）和IVF培养基的8.0％中发现细菌载量下降。天然精液和IVF培养基中细菌的最丰富属是乳杆菌，而其他样品中则以丙酸杆菌为多。金黄色葡萄球菌 仅在发炎患者的精液中发现。假单胞菌与高质量IVF胚胎的精子活力和α-变形杆菌呈负相关。结论我们的研究表明IVF不会在无菌环境中发生。常见细菌包括生精液和IVF培养基中的芽孢杆菌属，用于人工授精的已处理梭状芽胞杆菌和精子样本中的细菌类。金黄色葡萄球菌的存在。和Alteproteobacteria与临床结果有关，例如精子和胚胎质量。