Over thousands years, the function of microbiome (composition of microorganism and its genes on the body) in regulating the immune responses, metabolism and human behavior has more deceptive. The microbiota is located in various part of body, usually the gut microbiota exhibits the great importance, but microbiota is also present in skin, oral cavity, lungs, urogenital system and in amniotic fluid and placenta during pregnancy. The composition of microbiome depends upon two main factors, firstly the body site and secondly the host-dependent factors including genetic diversity, nutritional consumption, state of disease, geographical locality and bacterium species present. Any disturbance in the composition of microbiota will lead to serious infectious disease called as dsybiosis.
Determine if Placental microbiome has significant relationship between the pregnancy complication like preeclampsia, SGA and preterm birth with the bacteria.
The presence of bacteria in placenta was confirmed by culture dependent techniques, presence of microbes in tissue of placenta has describe the presence and absence of infection by using culture dependent and culture independent techniques. The DNA based analysis provide evidence that placenta have low biomass endogenous microbiota in the placenta. The species present in placenta include Lactobacillus species, Propionibacteria species and member of Enterobacteriaceae in healthy term pregnancy. The lactobacillus is relatively low in the tissue of placenta in preterm deliveries, gives a perspective of positive outcomes of pregnancy. (Pelzer, et al., 2017)
Researcher have evidence that transfer of bacteria from mother to infants, which is independent of delivery, for example vaginal or C-section. It is also believed that fetus delivery either by vagina or C-section, it contains common commensal bacteria like species that produced lactic acid. This said that fetus is not sterile, and different cocci gram positive bacteria also culture from umbilical cord of infant delivery through C-section. (Pelzer, et al., 2017).
Another studies to solve the controversy of presence of placental microbiome. The sample are collected from the women those have C-section deliver. The human and mouse sample are collected 28 humans placental sample and six murine placenta of mouse was under experimentation. All the human sample of placenta are amplified by using the 16s RNA gene. The human placenta is future analyzed by using gram staining, bacteria immunohistochemistry, electron microscopy and TaqMan RT-qPCR. And the mouse placenta is analyzed by 16s RNA gene amplification. The result was quiet interesting that none of placenta show the bacterial replication. None of these methods show the presence of any microbes in the placenta of human and mouse. Is it is said that fetal living environment like womb is sterile. (Kuperman, et al., 2020 Jan).
The presence S. agalactiae in placenta before delivery have clinical importance. The transmission of S. agalactiae from mother to infants is called perinatal transmission can cause the deadly sepsis in newborn baby. In united states different antibiotics are used by pregnant women against the S. agalactiae to prevent the death of the neonatal every year. More studies are required to know the association of organism in the tissue of placenta and the fetal and neonatal diseases. So there is no microbiome present in the placenta, bur during the C-section the bacteria from vagina moves into placenta. The different type of contamination occurs in the placenta, firstly the contamination during the deliver process, secondly the contamination during biopsy, thirdly the contamination during DNA extraction process, fourthly contamination by using reagents for amplification of DNA before the process of sequencing.
In conclusion, taking all the literature into account, it has been demonstrated that there is no evidence to support the presence of bacteria in the placenta and there is no significant relationship between the pregnancy complication like preeclampsia, SGA and preterm birth with the bacteria. However, most important pathogen called as S. agalactiae is present in the placenta of the pregnant women only about 5percent in women before the onset of labour. The placenta has sterile environment and so there is no alteration or placental microbiome because it totally not exists in the pregnant women.
(Lead image taken from Unplash)