Role for the mammalian female reproductive tract microbiome in pregnancy outcomes

Abstract

Since the discovery of the microbiome in humans, it has been studied in many mammalian species. Different microbiological communities with variable richness and diversity have been found among these species in distinct areas of the reproductive tract. Human studies have shown that the composition of the microbiome is dependent on body site and several host-related factors. Furthermore, specific phyla have been identified among the different species and within distinct areas of the female reproductive tract, but a “core” microbiome of the female reproductive tract has not been defined in any species. Moreover, the function of the microbiome in the reproductive tract is not yet fully understood. However, it has been suggested that a change in diversity of the microbiome and the presence or absence of specific microbial species might be useful indicators of pregnancy outcomes. Increased comprehensive knowledge of the microbiological communities in the female reproductive tract is needed since adverse outcomes represent a significant problem to many species, including livestock, exotic or endangered species, and humans. To the authors’ knowledge, a review combining current female reproductive tract microbiome data among different mammalian species has not been published yet. Herein is a comprehensive review of what is known in the field of the female reproductive microbiome and how it correlates with reproductive success or failure in mammals. Further studies may lead to optimization of therapies in the treatment of reproductive tract infections and pregnancy failure, and may create opportunities for novel approaches for improving reproductive efficiency in animals and people.

Persistent Breeding-Induced Endometritis in Mares—A Multifaceted Challenge: From Clinical Aspects to Immunopathogenesis and Pathobiology

“…G+: Gram-positive; G-: Gram-negative. vagina and uterus in mares can be explained by the open cervix and close communication between the uterine lumen and cranial vagina during estrus [88]. The uterine microbiome changes according to the stage of the estrous cycle and across studies [89,90].…”

“…The uterine microbiome of women and cows suffering from endometritis differs from that of healthy females [92], suggesting that endometritis is associated with commensal microbiome dysbiosis [88]. Invasion of the uterine cavity in mares and other mammals mostly occurs via ascending migration from the vagina [86,93], in association with one or more reproductive problems as described above.…”

Interrogating the bovine reproductive tract metagenomes using culture-independent approaches: a systematic review

“…Amplicon sequencing is a targeted sequencing approach focusing on a specific genomic region which are ubiquitous and discriminatory throughout the microbial population of interest [ 58 , 59 ]. The common target genes used in amplicon sequencing are 16S rRNA genes for bacteria [ 60 ], 18S rRNA genes for eukaryotes [ 61 ] and internal transcribed spacer (ITS) genes for fungi [ 62 ].…”

Core Microbiome of Slovak Holstein Friesian Breeding Bulls’ Semen

“…The term “metagenome” is usually defined as the collection of genomes and genes of the microorganisms from an environment [ 29 ] and the most powerful advent of this strategy lies in the possibility of decoding both culturable and unculturable species from the samples of interest [ 30 , 31 , 32 ]. Amplicon-based high-throughput sequencing, which is the base of metagenomics, targets a specific genomic region that is ubiquitous and discriminatory throughout the population of microorganisms that are of interest in the study [ 33 , 34 ]. The most common genomic targets for bacteria are 16S rRNA genes [ 35 ].…”