Human genital tracts microbiota: dysbiosis crucial for infertility

Abstract

Human body is colonized by trillions of microbes, influenced by several factors, both endogenous, as hormones and circadian regulation, and exogenous as, life-style habits and nutrition. The alteration of such factors can lead to microbial dysbiosis, a phenomenon which, in turn, represents a risk factor in many different pathologies including cancer, diabetes, autoimmune and cardiovascular disease, and infertility. Female microbiota dysbiosis (vaginal, endometrial, placental) and male microbiota dysbiosis (seminal fluid) can influence the fertility, determining a detrimental impact on various conditions, as pre-term birth, neonatal illnesses, and macroscopic sperm parameters impairments. Furthermore, unprotected sexual intercourse creates a bacterial exchange between partners, and, in addition, each partner can influence the microbiota composition of partner's reproductive tracts. This comprehensive overview of the effects of bacterial dysbiosis in both sexes and how partners might influence each other will allow for better personalization of infertility management.

Keywords: Dysbiosis; Fertility; Genital tracts; Lactobacillus; Microbiota.

Fig. 1

Impact of lifestyle, genetic factors, race, reproductive age, geographic localization and role of GH axis on microbiota influencing male and female sex maturation

Fig. 2

Effect of dysbiosis on female (A) and male (B) compound. Dysbiosis could influence the microbiota composition of other’s reproductive tracts. The effect of bacterial dysbiosis represents a risk factor for female fertility compartments with detrimental effects on uterus and placenta. In male dysbiosis affect macroscopic sperm parameters, with motility, morphology and concentration impairment