The complex microbiome from native semen to embryo culture environment in human in vitro fertilization procedure

Abstract

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.

The Association between Vaginal Dysbiosis and Reproductive Outcomes in Sub-Fertile Women Undergoing IVF-Treatment: A Systematic PRISMA Review and Meta-Analysis

“…Hence, a total of 11 citations were assessed for eligibility by examination of the full text. Two studies were removed due to study design [ 32 , 33 ] and three were removed as it was not possible to extract pregnancy outcome data for meta-analysis [ 34 , 35 , 36 ]. Two studies were based on the same study population [ 5 , 29 ], and only the initial publication was included [ 5 ], but data on LBR was extracted from the later study [ 29 ].…”

“…The authors of Moragianni et al [ 37 ] were contacted to clarify their definition of pregnancy and the authors provided relevant data for study inclusion. Additionally, we contacted authors of three studies [ 34 , 35 , 36 ] but received no response and consequently their data could not be evaluated in the present meta-analysis.…”

Lactobacillus iners and gasseri, Prevotella bivia and HPV Belong to the Microbiological Signature Negatively Affecting Human Reproduction

“…The identified bacteria within the follicular fluids and embryo culture media overlapped, in part, with the vaginal microbiome, supporting the concept that the bacterial colonization of the upper female genital tract could be a consequence of prior infertility treatment procedures, with bacteria being introduced into the ovary at the time of oocyte retrieval, or could depend on haematogenous bacterial dissemination, as is favored by the significant increase in the ovarian blood supply from the proliferative period of one menstrual cycle to the proliferative phase of the following cycle [1,39]. Besides this, it has been demonstrated that L. gasseri significantly reduces sperm motility [40] and that, as a whole, the seminal microbiome used for IVF impacts the embryo quality and pregnancy rates [41]. Indeed, the male factor is considered as a potential predictor of the IVF's outcome [42,43].…”

Microbiota and Human Reproduction: The Case of Female Infertility

“…They found that the vaginal microbiome of idiopathic infertile women differed from controls, whereas the semen not; in addition, they found, among the vaginal microbiome of idiopathic infertile women different patterns of Lactobacillus species, Lactobacillus crispatus being associated to the higher rate of intrauterine insemination success [ 96 ]. More recently, Štšepetova et al analyzed the microbiome of native semen samples used for IVF, processed semen samples, and IVF culture media, with the aim to associate them with IVF embryo quality and pregnancy rates [ 101 ]. The study highlighted several bacterial changes in the IVF samples; in particular, the presence of Staphylococcus spp.…”